UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 4)*

Oi S.A.

(Name of Issuer)

Common Shares, no par value

(Title of Class of Securities)

670851 104**

(CUSIP Number)

Fernando Magalhães Portella, Investor Relations Director

Telemar Participações S.A.,

Praia de Botafogo 300, 11th floor, sala 1101 (parte)

Botafogo, Rio de Janeiro, RJ, Brazil 22250-040

Tel: +55 21 3873-9016

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

September 8, 2014

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

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Preliminary Statement

This Amendment No. 4 to Schedule 13D (this “Amendment”) filed by Telemar Participações S.A. (“TmarPart”) and Valverde Participações S.A., a wholly-owned subsidiary of TmarPart (“Valverde,” and together with TmarPart, the “Reporting Persons”) amends the Statement on Schedule 13D filed with the Securities and Exchange Commission on November 27, 2009 (the “Initial 13D”) by TmarPart, Tele Norte Leste Participações S.A. (“TNL”), Telemar Norte Leste S.A. (“Telemar”) and Coari Participações S.A. (“Coari”), as amended by Amendment No. 1 to Schedule 13D (“Amendment No. 1”) filed with the Securities and Exchange Commission on February 29, 2012 by the Reporting Persons, as amended by Amendment No. 2 to Schedule 13D (“Amendment No. 2) filed with the Securities and Exchange Commission on October 8, 2013, as amended by Amendment No. 3 to Schedule 13D (“Amendment No. 3”, the Initial 13D as amended by Amendment No. 1, Amendment No. 2, Amendment No. 3 and as further amended by this Amendment, this “Statement”) filed with the Securities and Exchange Commission on February 27, 2014 by the Reporting Persons, by furnishing the information set forth below. Except as otherwise specified in this Amendment, all previous Items are unchanged. Capitalized terms used herein which are not defined herein have the meanings given to them in the Initial 13D, Amendment No. 1, Amendment No. 2 and Amendment No. 3.

On February 19, 2014, amendments to the Shareholders’ Agreements of TmarPart were signed, establishing the commitment of the shareholders of TmarPart to exercise their voting rights in TmarPart, and also for their representatives on the Boards of Directors of Oi S.A. (“Oi”) and TmarPart to exercise their rights to vote, in order to approve the Business Combination as well as agreements to terminate these Shareholders’ Agreements upon the completion of the Business Combination. In addition, Portugal Telecom, Caravelas Fundo de Investimento em Ações (“Caravelas”), an investment vehicle managed by Banco BTG Pactual S.A., Bratel, TmarPart, Andrade Gutierrez S.A. (“AGSA”) and Jereissati Telecom S.A. entered into a Temporary Voting Agreement to take all the actions required for among other things, the effective completion of the Merger of Shares.

As part of the Business Combination, on May 5, 2014, Oi completed a share capital increase (the “Oi Capital Increase”), pursuant to which Portugal Telecom subscribed for the newly-issued shares of Oi through the contribution by Portugal Telecom to Oi of all of the shares of PT Portugal, SGPS, S.A. (“PT Portugal”), which, at the time of the transfer, owned all of (i) Portugal Telecom’s operational assets, except direct and indirect interests held in Oi, Contax Participações S.A. and Bratel, BV and (ii) Portugal Telecom’s liabilities as of the date of contribution. The assets of PT Portugal as of the date of the contribution of PT Portugal by Portugal Telecom to Oi in the Oi Capital Increase included an investment in commercial paper in the aggregate amount of €897 million issued by Rio Forte Investments S.A. (“Rio Forte”). In July 2014, the cure period for payment of the commercial paper held by PT Portugal and Portugal Telecom International Finance B.V. (“PTIF”) (together, the “Oi Subsidiaries”) expired without this commercial paper having been paid.

As a result, on July 14, 2014, Oi and Portugal Telecom entered into a memorandum of understanding (“Second MOU”) to establish the basis of an agreement between them in relation to the commercial paper of Rio Forte (the “Securities”). The parties agreed that the principal documents would be an exchange agreement, pursuant to which Oi would exchange the Securities for Common Shares and Oi preferred shares held by Portugal Telecom (the “Exchange Agreement”), and a call option agreement, pursuant to which Oi would grant to Portugal Telecom an option to purchase Oi shares in the same amount and type as the exchanged shares (the “Call Option Agreement”, together with the Exchange Agreement, the “Definitive Agreements”).

On September 8, 2014, an extraordinary shareholders’ meeting of Portugal Telecom approved the execution by Portugal Telecom of the Definitive Agreements. The Definitive Agreements were executed on September 8, 2014.

As a result of the transactions contemplated in the Definitive Agreements, the agreements entered into on February 19, 2014 were amended to provide for, among other things: (i) the extension of deadlines for the completion of the Business Combination; (ii) the elimination of references to the abandoned merger of Portugal Telecom into TmarPart; and (iii) the limitation of voting rights of Portugal Telecom in the by-laws of TmarPart to a maximum of 7.5% (the “Business Combination Agreements”).

The Reporting Persons are filing this Amendment to revise information previously reported in light of the approval and execution of the Definitive Agreements and the Business Combination Agreements.

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ITEM 4. PURPOSE OF TRANSACTION

Item 4 of Amendment No. 3 is amended to add the following paragraphs:

Definitive Agreements Implementing the Second MOU

The Definitive Agreements are intended to permit the parties to proceed with the implementation of the Business Combination, including the Merger of Shares, with the necessary adjustments.

The Exchange Agreement among the Oi Subsidiaries, Portugal Telecom, Oi and TmarPart provides for an exchange pursuant to which Portugal Telecom will acquire the Securities from the Oi Subsidiaries and, in exchange, Portugal Telecom will transfer to the Oi Subsidiaries the Exchanged Shares (defined below) and (2) the Call Option Agreement among the Oi Subsidiaries, Portugal Telecom, Oi and TmarPart provides that the Oi Subsidiaries will grant Portugal Telecom a call option to purchase Common Shares and Oi preferred shares of the same number and class as the Exchanged Shares (or upon completion of the Merger of Shares, common shares of TmarPart) (the “Call Option”).

Exchange Agreement

The Exchange Agreement provides that, subject to the conditions described under “Conditions to the Exchange, the Exchange Agreement and the Call Option Agreement” below, the Oi Subsidiaries and Portugal Telecom will effect the Exchange, whereby the Oi Subsidiaries will transfer the Securities to Portugal Telecom and Portugal Telecom will transfer to the Oi Subsidiaries an aggregate of 474,348,720 Common Shares and 948,697,440 Oi preferred shares, representing 16.9% of the outstanding share capital of Oi, including 17.1% of the outstanding voting capital of Oi prior to giving effect to the Exchange (or in the event that the completion of the Exchange occurs following the Merger of Shares, 1,348,193,932 common shares of TmarPart) (collectively, the “Exchanged Shares”).

The Exchange of the Exchanged Shares for the Securities is expected to occur no later than three business days after all the conditions set forth under “Conditions to the Exchange, the Exchange Agreement and the Call Option Agreement” below have been satisfied. The Exchange Agreement may be terminated by Portugal Telecom and/or by Oi and TmarPart if the Exchange does not occur by March 31, 2015.

The Exchange Agreement further provides that once the Exchange has been consummated, Oi, TmarPart and the Oi Subsidiaries will grant Portugal Telecom and its directors a release in relation to the subscription for or acquisition of the Securities and their later contribution to Oi in the Oi Capital Increase, as well as an express waiver by Oi and the Oi Subsidiaries of any right to file a claim or to claim indemnification (with the express and exclusive exception of claims relating to the right of recourse against Portugal Telecom with respect to third-party claims) by virtue of the Securities and their contribution to Oi in the Oi Capital Increase or any omissions or incomplete information related specifically to the Securities, their situation and the risks involved.

The Exchange Agreement is governed by Brazilian law, and any dispute with respect to the Exchange Agreement is to be resolved through arbitration in Rio de Janeiro, Brazil before an arbitration panel administered by the Brazil-Canada Chamber of Commerce.

Call Option Agreement

Pursuant to the Call Option Agreement, Oi and the Oi Subsidiaries have granted to Portugal Telecom (subject to the condition described under “Conditions to the Exchange, the Exchange Agreement and the Call Option Agreement” below) a nontransferable Call Option to acquire the Exchanged Shares (collectively, the “Option Shares”). The total number of Option Shares is subject to adjustment to reflect any split or reverse split of shares of Oi or TmarPart, as applicable.

Portugal Telecom will be entitled to exercise the Call Option, in whole or in part, at any time, during a period of six years from the date of the consummation of the Exchange (the “Closing Date”). The original number of Option Shares that Portugal Telecom is entitled to purchase pursuant to the Call Option will be reduced (1) by 10% of the

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original number of Option Shares upon the first anniversary of the Closing Date and (2) by 18% of the original number of Option Shares on each successive anniversary of the Closing Date thereafter, beginning on the second anniversary of the Closing Date.

The Call Option exercise price will be R$1.8529 per Oi preferred share and R$2.0104 per Common Share (and, if applicable, R$2.0104 per common share issued by TmarPart), in each case adjusted by the Brazilian Interbank Certificate of Deposit (Certificado de Depósito Interbancário) rate plus 1.5% per annum, calculated pro rata, from the date of the Exchange and through the date of effective payment of the exercise price, in whole or in part, of the Call Option. The exercise price of the Call Option must be paid in cash, in immediately available funds, on the date of the transfer of the Option Shares.

The Call Option Agreement further provides for a possibility of settlement in cash by the grantors, in the event that, upon exercise of the Call Option by Portugal Telecom, the Oi Subsidiaries and/or any other subsidiary of Oi do not hold in treasury a sufficient number of Oi shares or TmarPart shares, as applicable, to deliver to Portugal Telecom. In such case, the Call Option may be settled by payment in cash by the Oi Subsidiaries to Portugal Telecom of an amount corresponding to the difference between the market price for the Option Shares on the business day immediately preceding the exercise of the Call Option and the applicable exercise price corresponding to those shares.

So long as the Call Option is in effect, Portugal Telecom will be precluded from acquiring Oi shares or TmarPart shares, directly or indirectly, other than through the exercise of the Call Option. Portugal Telecom may not assign or transfer the Call Option and may not grant any rights associated with the Call Option, including any guarantees, without Oi’s consent, except that Portugal Telecom may make a one-time assignment to a subsidiary of Portugal Telecom at least 99% of the voting and share capital of which is held by Portugal Telecom, and so long as Portugal Telecom remains jointly and severally liable under the Call Option Agreement with the subsidiary. If Portugal Telecom issues, directly or indirectly, derivative instruments indexed, backed by or related to shares of Oi or TmarPart, it must immediately use all the financial proceeds received, directly or indirectly, in these transactions for the acquisition of Option Shares.

Oi may terminate the Call Option if (1) the bylaws of Portugal Telecom are voluntarily amended to delete or amend the provision that limits the voting rights of any shareholder to 10% of the total voting rights of Portugal Telecom, (2) Portugal Telecom begins to compete with Oi; or (3) Portugal Telecom breaches certain obligations under the Call Option Agreement.

The Call Option Agreement is governed by Brazilian law, and any dispute with respect to the Call Option Agreement is to be resolved through arbitration in Rio de Janeiro, Brazil before an arbitration panel administered by the Brazil-Canada Chamber of Commerce.

As further detailed under “Conditions to the Exchange, the Exchange Agreement and the Call Option Agreement” below, the Call Option will automatically expire if the Exchange is not implemented by March 31, 2015.

Conditions to the Exchange, the Exchange Agreement and the Call Option Agreement

The execution of the Exchange Agreement and the Call Option Agreement required the approval of (1) the board of directors of Portugal Telecom, which approved the terms and conditions of the Definitive Agreements on July 28, 2014 and approved the proposal submitted to the extraordinary general shareholders’ meeting of Portugal Telecom on August 13, 2014, (2) the shareholders of Portugal Telecom, which approved Definitive Agreements at an extraordinary general shareholders’ meeting on September 8, 2014 and (3) the board of directors of Oi, which approved Definitive Agreements on September 8, 2014.

As a condition to the execution of the Exchange Agreement, the following matters were also approved by a pre-meeting (reunião prévia) of the shareholders of TmarPart held on September 3, 2014: (1) if feasible, the listing of TmarPart on the BM&FBovespa, the Euronext Lisbon and the New York Stock Exchange so as to allow the implementation of an alternative structure for integrating the shareholder bases of Portugal Telecom and TmarPart after the Merger of Shares, (2) amendments to the bylaws of TmarPart to include a limitation of 7.5% on the voting

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rights applicable to (a) Portugal Telecom, and (b) any other shareholder who receives a percentage interest in TmarPart greater than 15% of TmarPart’s share capital due to any future integration of the shareholder bases of Portugal Telecom and TmarPart, excluding any shares of TmarPart already held by that shareholder or that are acquired through other means, and (3) the amendments to the shareholders’ agreements, the temporary voting agreement and the agreements relating to the termination of the shareholders’ agreements of TmarPart, all of which were entered into on February 19, 2014, as further described under “Amendments to the Business Combination Agreements” of Item 6 below.

In addition to the corporate approvals described above and the execution of the Definitive Agreements, the completion of the Exchange and the effectiveness of the Call Option are further subject to the approval of the Brazilian Securities Commission (Comissão de Valores Mobiliários, or “CVM”), of (1) the receipt of the Exchanged Shares by the Oi Subsidiaries, (2) the maintenance in treasury of a number of Oi shares (and, after the Merger of Shares, of TmarPart shares) equivalent to the maximum number of Exchanged Shares, and (3) the grant of the Call Option by the Oi Subsidiaries to Portugal Telecom for a number of Oi shares (and, after the Merger of Shares, of TmarPart shares) equivalent to the maximum number of Exchanged Shares. In accordance with the terms set forth in the Definitive Agreements, if CVM approval cannot be obtained by March 31, 2015, the Exchange will not be consummated and the Call Option will not become effective.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER

Item 5 is hereby amended and restated in its entirety as follows:

As of September 8, 2014, the total number of issued and outstanding Common Shares is 2,777,302,504, excluding 84,250,695 Common Shares held in treasury.

As of September 8, 2014, Valverde beneficially owns, and has the sole power to vote and dispose of 40,814,953 Common Shares, representing 1.47% of the issued and outstanding Common Shares.

Valverde does not have a board of directors or other equivalent body. Other than as set forth in the table below, as of September 8, 2014, none of the executive officers of Valverde beneficially owns any Common Shares. Valverde disclaims beneficial ownership of such securities of the Issuer beneficially owned by such executive officers.

TmarPart:

As of September 8, 2014, TmarPart owns all of the outstanding common shares of Valverde and beneficially owns, and has the sole power to vote and dispose of 249,734,835 Common Shares, representing 8.99% of the issued and outstanding Common Shares. As a result, TmarPart beneficially owns, and has the sole power to vote and dispose of, 290,549,788 Common Shares, representing 10.46% of the issued and outstanding Common Shares.

Other than as set forth in the table below, as of September 8, 2014, none of the directors and executive officers of TmarPart beneficially owns any Common Shares. The numbers of Common Shares beneficially owned by directors and executive officers of TmarPart are set forth below. TmarPart disclaims beneficial ownership of such securities of the Issuer beneficially owned by such directors and executive officers.

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Except as set forth in this Statement, none of the Reporting Persons nor, to the Reporting Persons best knowledge, any of the persons listed in Exhibit 99.2 hereto, has engaged in any transaction during the past 60 days in any Common Shares.

ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF THE ISSUER

Item 6 is hereby amended by adding the following paragraphs at the end thereof:

Exchange Agreement

On September 8, 2014, the Oi Subsidiaries, Portugal Telecom, Oi and TmarPart executed the Exchange Agreement described in Item 4 of this Amendment, which description is incorporated by reference in this Item 6. The description of the Exchange Agreement is a summary only and is qualified in its entirety by the terms of the Exchange Agreement, which is filed as Exhibit 99.17 to this Amendment and is incorporated herein by reference.

Call Option Agreement

On September 8, 2014, the Oi Subsidiaries, Portugal Telecom, Oi and TmarPart executed the Call Option Agreement described in Item 4 of this Amendment, which description is incorporated by reference in this Item 6. The description of the Call Option Agreement is a summary only and is qualified in its entirety by the terms of the Call Option Agreement, which is filed as Exhibit 99.18 to this Amendment and is incorporated herein by reference.

Amendments to the Business Combination Agreements

As described under “Conditions to the Exchange, the Exchange Agreement and the Call Option Agreement” above, the execution of the Definitive Agreements was subject to, among other things, the approval by a pre-meeting (reunião prévia) of the shareholders of TmarPart of certain amendments to the shareholders’ agreements, the temporary voting agreement and the agreements relating to the termination of the shareholders’ agreements of TmarPart, all of which were entered into on February 19, 2014, in order to account for the transactions contemplated by the Definitive Agreements and the changes to the original structure of the Business Combination.

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As previously disclosed in Amendment No. 2, the Global Shareholders’ Agreement, the Control Group Shareholders’ Agreement, the PASA Shareholders’ Agreement and the EDSP75 Shareholders’ Agreement were amended on February 19, 2014. As amended, the agreements provided that the parties thereto agreed to exercise their voting rights to approve each step of the Business Combination and addressed the consequences in the event that the Business Combination or any of its steps is not be completed by December 31, 2014.

In addition, on February 19, 2014, the parties to each of the shareholders’ agreements described above entered into agreements to terminate each such shareholders’ agreement, subject to the satisfaction of certain conditions precedent relating to the several steps of the Business Combination, including the completion of the Portugal Telecom Merger. On the same date, Portugal Telecom executed a temporary voting agreement with Caravelas, Bratel, TmarPart, AG, Jereissati and, as intervening party, Oi, whereby the parties thereto agreed to, among other things, (1) vote in favor of the Merger of Shares and (2) vote in favor of the Portugal Telecom Merger. The temporary voting agreement was to remain in effect until the earlier of the Portugal Telecom Merger and December 31, 2014.

At the pre-meeting (reunião prévia) of the shareholders of TmarPart held on September 3, 2014, the shareholders of TmarPart decided to amend the Business Combination Agreements as initially described in Amendment No. 2, as follows:

These amendments to the Business Combination Agreements were executed on September 8, 2014. The description of the amendments to the Business Combination Agreements above is a summary only and is qualified in its entirety by the terms of the amendments themselves, which are filed as Exhibits 99.6, 99.8, 99.12, 99.14 and 99.16 to this Amendment and are incorporated herein by reference.

Terms of Commitment

On September 8, 2014, Portugal Telecom, Oi and TmarPart executed a Terms of Commitment agreement (the “Terms of Commitment”) that contains certain undertakings to enable the parties to pursue the objective of integrating the shareholder bases of Oi and Portugal Telecom.

Under the Terms of Commitment, the parties agree to use best efforts to obtain the listing of TmarPart’s shares on the NovoMercado segment of the BM&FBovespa, Euronext Lisbon and the New York Stock Exchange concurrently with the approval of the Merger of Shares by the shareholders of Oi and TmarPart. In addition, the parties agree to perform any acts, provide any required information, prepare all necessary documentation and file all necessary filings with all appropriate governmental authorities to implement these listings and the integration of the shareholder bases of Oi and Portugal Telecom, including, among other things, the preparation and filing of any prospectuses and registration statements with the CVM, the CMVM and the SEC.

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In addition, Oi, in its capacity as shareholder of Portugal Telecom, undertakes to attend any meeting of the shareholders of Portugal Telecom specifically convened to consider legally permissible alternative structures to the Portugal Telecom Merger proposed by Portugal Telecom and to vote in favor of the proposed structure, to the extent such vote is not contrary to Oi’s legitimate interests.

This Terms of Commitment will remain in effect until the integration of the shareholder bases of Portugal Telecom and TmarPart has been fully completed, including in respect of any Oi or TmarPart shares that Portugal Telecom may acquire as a result of its exercise of the Call Option.

The Terms of Commitment are governed by Brazilian law, and any dispute with respect to the Terms of Commitment is to be resolved through arbitration in Rio de Janeiro, Brazil before an arbitration panel administered by the Brazil-Canada Chamber of Commerce.

The description of the Terms of Commitment is a summary only and is qualified in its entirety by the terms of the Terms of Commitment, which is filed as Exhibit 99.19 to this Amendment and is incorporated herein by reference.

ITEM 7. MATERIALS TO BE FILED AS EXHIBITS

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After reasonable inquiry and to the best of my knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

Dated: September 17, 2014

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Exhibit 99.2

DIRECTORS AND EXECUTIVE OFFICERS OF THE REPORTING PERSONS

The following information is provided for each of the directors and executive officers of the Reporting Persons:

Directors and Executive Officers of Telemar Participações S.A.

All of the following persons are citizens of the Federative Republic of Brazil, except for Pedro Guimarães e Melo de Oliveira Guterres, who is a citizen of Portugal.

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Executive Officers of Valverde Participações S.A.

All of the following persons are citizens of the Federative Republic of Brazil.

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Exhibit 99.6

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original document was prepared in Portuguese and in case of any divergence, discrepancy or difference between this version and the Portuguese version, the Portuguese version shall prevail. The Portuguese version is the only valid and complete version and shall prevail for any and all purposes. There is no assurance as to the accuracy, reliability or completeness of the translation. Any person reading this translation and relying on it should do so at his or her own risk.

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT

OF TELEMAR PARTICIPAÇÕES S.A.

BETWEEN

AG TELECOM PARTICIPAÇÕES S.A.

LF TEL S.A.

FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL

AND, AS INTERVENING PARTY,

TELEMAR PARTICIPAÇÕES S.A.

EXECUTED ON SEPTEMBER 8, 2014.

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT

OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED ON APRIL 25. 2008 AND AMENDED ON JANUARY 25, 2011 AND ON FEBRUARY 19, 2014.

By this instrument:

And, as “First Intervening Party”,

WHEREAS:

THE PARTIES have agreed to enter into this 3^rd Amendment to the Shareholders Agreement of Telemar Participações S.A. dated April 25, 2008 and amended on January 25, 2011 and on February 14, 2014, (“the 3^rd Amendment”), which shall be governed by the following terms and conditions:

CLAUSE ONE – AMENDMENT OF CLAUSE XVII

1.1. The Parties resolve to amend Clause XVII of the AG/LF/FATL Shareholders Agreement, establishing special provisions related to the Transaction, so as to change the cut-off date established therein and include reference to changes to certain stages of the Transaction, as approved in prior meetings held on September 3, 2014, as a result of which Clause XVII shall now read as follows:

“CLAUSE XVII

SPECIAL PROVISIONS RELATED TO THE TRANSACTION FOR THE COMBINATION OF THE ACTIVITIES OF OI AND OF PORTUGAL TELECOM SGPS

17.1 The Shareholders undertake the firm, irrevocable and irreversible commitment of exercising their respective voting rights in the Company, as well as having their representatives on the Board of Directors of the Company and of the Relevant Subsidiaries, that will be considered a Relevant Controlled Company for all purposes of this General Shareholders Agreement, irrespective of the ownership percentage that the Company has in the capital stock of Oi, exercise their respective voting rights, so as to approve the Transaction that will unify the activities and businesses carried out by Oi and by Portugal Telecom SGPS, particularly in Brazil, Portugal and Africa, under the terms of the Prior Meeting and the Prior General Meeting held on February 19, 2014, with the amendments approved by the Prior Meeting and Prior General Meeting held on September 3, 2014.

17.1.1 Until the consummation of the Merger of Oi Shares by CorpCo, and irrespective of the shareholding percentage that each Shareholder has in the Company throughout the steps of the Transaction, for purposes of the exercise of the voting rights provided in the AG/LF/FATL Shareholders Agreement and in the General Shareholders Agreement, each one of the Shareholders shall be ascribed the number of votes it held on February 19,

2014, i.e. the date of execution of the 2^nd Amendment, observing the special quorums provided in the General Shareholders Agreement in accordance with the shareholding percentage held by each one of the Shareholders on that date.

17.2 In the event judicial, administrative or arbitration decisions are rendered, even if provisional, which prevent the implementation of any of the steps of the Transaction, or in any other manner affect or restrict the effects thereof, the Shareholders undertake the firm, irrevocable and irreversible commitment of exercising their respective voting rights so as to have the Company and/or the Relevant Subsidiaries adopt all measures necessary for implementing the Transaction, collaborating in an active, efficient and timely manner so that the Company, and/or Relevant Subsidiaries eliminate, as soon as possible, the effects of said judicial, administrative or arbitration measure(s).

17.3 The Shareholders also undertake the firm, irrevocable and irreversible commitment of exercising their respective voting rights in the Company, as well as having their representatives in the Board of Directors of the Company and of the Relevant Subsidiaries exercise their respective voting rights, so as to maintain the ordinary course of business of the Company and of the Relevant Subsidiaries, refraining from taking any measure or performing any act that could impair or otherwise adversely affect the consummation of the Transaction.

17.4 The Shareholders acknowledge and agree that all steps of the Restructuring of Telemar Participações as described in the Recital IX of the 2^nd Amendment to Telemar Participações S.A. Shareholders Agreement, and the Merger of Oi Shares by CorpCo are tied to each other and must be implemented simultaneously. Accordingly, the Shareholders agree that the implementation and efficiency of each one of the steps of the Restructuring of Telemar Participações and the Merger of Oi Shares by CorpCo are conditioned upon the actual approval and implementation of one another.

17.5 Should the Capital Increase of Oi be effected and any of the subsequent steps of the Transaction, i.e., the Restructuring of Telemar Participações and the Merger of Oi Shares by CorpCo, not be concluded by March 31, 2015 (the “Cut-off Date”), the Shareholders shall use their best efforts to implement the restructuring of Telemar Participações and of Oi to achieve the same objectives of the Transaction, although they will be released from the obligation of implementing the Restructuring of Telemar Participações and the Merger of Oi Shares by CorpCo, as approved in the Prior General Meeting held on February 19, 2014, with the amendments approved by the Prior AG/LF/FASS Meeting and in the Prior General Meeting held on September 3, 2014.

17.6 The Shareholders and the Company declare they are aware of the contents of the Temporary Voting Agreement of the Shareholders of Oi S.A. and of Telemar Participações S.A. (to be referred to as “CorpCo”) between Caravelas Fundo de Investimento em Ações, Portugal Telecom SGPS S.A., Bratel Brasil S.A., Telemar Participações S.A., Andrade Gutierrez S.A. and Jereissati Telecom S.A., executed on February 19, 2014 and amended on September 3, 2014, such document being filed at the head offices of Oi and recorded in the respective share ownership registries.”

CLAUSE TWO – GENERAL PROVISIONS

2.1 Capitalized terms not expressly defined in this 3^rd Amendment shall have the meaning attributed to them in the AG/LF/FATL Shareholders Agreement and in the 1^st and 2^nd Amendments.

2.2 All other terms and conditions of the AG/LF/FATL Shareholders Agreement remain in force and are hereby ratified by the Shareholders.

2.3 This 3^rd Amendment shall be irrevocable and irreversible for the undersigned parties and their respective successors under any title.

IN WITNESS WHEREOF, the Parties have executed this instrument in 4 (four) counterparts of equal form and content in the presence of the 2 (two) undersigned witness.

Rio de Janeiro, September 8, 2014.

AG TELECOM PARTICIPAÇÕES S.A.

Signature page of the 3^rd Amendment to the Shareholders Agreement of Telemar Participações S.A., executed between AG Telecom Participações S.A., LF Tel S.A., Fundação Atlântico de Seguridade Social and Telemar Participações S.A. on September 8, 2014.

LF TEL S.A.

FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL

TELEMAR PARTICIPAÇÕES S.A.

Exhibit 99.8

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original document was prepared in Portuguese and in case of any divergence, discrepancy or difference between this version and the Portuguese version, the Portuguese version shall prevail. The Portuguese version is the only valid and complete version and shall prevail for any and all purposes. There is no assurance as to the accuracy, reliability or completeness of the translation. Any person reading this translation and relying on it should do so at his or her own risk.

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A.

SHAREHOLDERS AGREEMENT EXECUTED ON FEBRUARY 19, 2014

BETWEEN

AG TELECOM PARTICIPAÇÕES S.A.

LF TEL S.A.

FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL

AND, AS INTERVENING PARTY,

TELEMAR PARTICIPAÇÕES S.A.

EXECUTED ON SEPTEMBER 8, 2014

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT,

EXECUTED ON APRIL 25, 2008 AND AMENDED ON JANUARY 25, 2011.

By this instrument:

And, as “Intervening-Consenting Party”,

WHEREAS:

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The PARTIES have agreed to enter into this 1^st Amendment to the Termination of the Telemar Participações S.A. Shareholders Agreement dated April 25, 2008 and amended on January 25, 2011 (the “1^st Amendment”) which shall be governed by the following terms and conditions:

CLAUSE ONE – AMENDMENT OF CLAUSE TWO

1.1. The Shareholders agree to amend Clause Two of the Termination, which governs the condition precedent to the effectiveness of said Termination, to remove references to the Merger of Portugal Telecom by CorpCo, as a result of which Clause Two shall now read as follows:

“CLAUSE TWO – EFFICACY

2.1. This Termination is signed under the condition subsequent set forth in Article 125 et seq. of the Civil Code and shall only be effective following the actual implementation of the Merger of the Oi Shares by CorpCo.”

CLAUSE TWO – GENERAL PROVISIONS

2.1 Capitalized terms not expressly defined in this 1^st Amendment shall have the meaning attributed to them in the Termination.

IN WITNESS WHEREOF, the Parties have executed this instrument in 4 (four) counterparts of equal form and content in the presence of the 2 (two) undersigned witness.

3

Rio de Janeiro, September 8, 2014.

AG TELECOM PARTICIPAÇÕES S.A.

4

Signature page of the 1^st Amendment to the Termination of the Telemar Participações S.A. Shareholders Agreement executed on February 19, 2014, executed between AG Telecom Participações S.A., LF Tel S.A., Fundação Atlântico de Seguridade Social and Telemar Participações S.A. on September 8, 2014.

LF TEL S.A.

FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL

TELEMAR PARTICIPAÇÕES S.A.

5

Exhibit 99.12

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original document was prepared in Portuguese and in case of any divergence, discrepancy or difference between this version and the Portuguese version, the Portuguese version shall prevail. The Portuguese version is the only valid and complete version and shall prevail for any and all purposes. There is no assurance as to the accuracy, reliability or completeness of the translation. Any person reading this translation and relying on it should do so at his or her own risk.

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT

OF TELEMAR PARTICIPAÇÕES S.A.

BETWEEN

AG TELECOM PARTICIPAÇÕES S.A.

ANDRADE GUTIERREZ S.A.

BNDES PARTICIPAÇÕES S.A. – BNDESPAR

CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI

FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL

FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF

FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS

JEREISSATI TELECOM S.A.

LF TEL S.A.

BRATEL BRASIL S.A.

AND, AS INTERVENING PARTIES,

TELEMAR PARTICIPAÇÕES S.A.

PORTUGAL TELECOM, SGPS S.A.

EXECUTED ON SEPTEMBER 8, 2014.

3^RD AMENDMENT TO THE TELEMAR PARTICIPAÇÕES S.A.

SHAREHOLDERS AGREEMENT,

EXECUTED ON APRIL 25, 2008 AND AMENDED ON JANUARY 25, 2011 AND ON FEBRUARY 19, 2014.

By this instrument:

2

individually also referred to as a “Party” or “Shareholder” and collectively referred to as the “Parties” or “Shareholders”, and, further,

as “Intervening Parties”,

3

WHEREAS:

THE PARTIES have agreed to enter into this 3^rd Amendment to the Shareholders Agreement of Telemar Participações S.A. dated April 25, 2008 and amended on January 25, 2011 and on February 14, 2014 (the “3^rd Amendment”), which shall be governed by the following terms and conditions:

CLAUSE ONE – CLAUSE XXV

“CLAUSE XXV

SPECIAL PROVISIONS RELATED TO THE TRANSACTION FOR THE COMBINATION OF THE ACTIVITIES OF OI AND OF PORTUGAL TELECOM SGPS

25.1 The Shareholders undertake the firm, irrevocable and irreversible commitment of exercising their respective voting rights in the Company, as well as having their representatives on the Board of Directors of the Company and of the Relevant Subsidiaries and of Oi – who shall be considered a Relevant Subsidiary for all purposes of the General Shareholders Agreement, irrespective of the ownership percentage that the Company has in the capital stock of Oi – exercise their respective voting rights, so as

4

to approve the Transaction that will unify the activities and businesses carried out by Oi and by Portugal Telecom SGPS, particularly in Brazil, Portugal and Africa, under the terms of the Prior General Meeting held on February 19, 2014, with the amendments approved by the Prior General Meeting held on September 3, 2014.

25.1.1 Until the consummation of the Merger of Oi Shares by Corpco, and irrespective of the shareholding percentage that each Shareholder has in the Company throughout the steps of the Transaction, for purposes of the exercise of the voting rights provided in the General Shareholders Agreement, each one of the Shareholders shall be ascribed the number of votes it held on February 19, 2014, observing the special quorums provided in the General Shareholders Agreement in accordance with the shareholding percentage held by each one of the Shareholders on that date. Likewise, all other political rights held by the Shareholders as of February 19, 2014 shall be maintained, including the right to appoint members to the corporate bodies of the Company, Oi and the Relevant Subsidiaries.

25.2 In the event judicial, administrative or arbitration decisions are rendered, even if provisional, which prevent the implementation of any of the steps of the Transaction, or in any other manner affect or restrict the effects thereof, the Shareholders undertake the firm, irrevocable and irreversible commitment of exercising their respective voting rights so as to have the Company and/or the Relevant Subsidiaries adopt all measures necessary for implementing the Transaction, collaborating in an active, efficient and timely manner so that the Company and/or Relevant Subsidiaries eliminate, as soon as possible, the effects of said judicial, administrative or arbitration measure(s).

25.3 The Shareholders also undertake the firm, irrevocable and irreversible commitment of exercising their respective voting rights in the Company, as well as having their representatives on the Board of Directors of the Company and of the Relevant Subsidiaries exercise their respective voting rights, so as to maintain the ordinary course of business of the Company and of the Relevant Subsidiaries, refraining from taking any measure or performing any act that could impair or otherwise adversely affect the consummation of the Transaction.

25.4 The Shareholders acknowledge and agree that all steps of the Restructuring of Telemar Participações as described in the Recital VIII of the 2^nd Amendment to Telemar Participações Shareholders Agreement, and the Merger of Oi Shares by Corpco are tied to each other and must be implemented simultaneously. Accordingly, the Shareholders agree that the implementation and efficiency of each one of the steps of the Restructuring of Telemar Participações and the Merger of Oi Shares by Corpco are conditioned upon the actual approval and implementation of one another.

25.5 Should the Capital Increase of Oi be effected and any of the subsequent steps of the Transaction, i.e., the Restructuring of Telemar Participações and the Merger of Oi Shares by Corpco, not be concluded by March 31, 2015 (the “Cut-off Date”), the Shareholders shall use their best efforts to implement the restructuring of Telemar Participações and of Oi S.A. to achieve the same objectives of the Transaction, although

5

they will be released from the obligation of implementing the Restructuring of Telemar Participações and the Merger of Oi Shares by Corpco, as approved in the Prior General Meeting held on February 19, 2014, with the amendments approved by the Prior General Meeting held on September 3, 2014.

25.6 Upon occurrence of the event provided in Clause 25.5, the special quorums provided in the General Shareholders Agreement shall be adjusted to take into account the shareholding percentage the Shareholders AG TELECOM, LF TEL, FATL, BRATEL BRASIL, BNDESPAR, PREVI, PETROS and FUNCEF had on the Cut-Off Date, so that such Shareholders have the same political rights as they had on the date of execution of the 2^nd Amendment, provided that they have not reduced their respective ownership interests by the Cut-Off Date, as a result of selling their Affected Shares to third parties who are not original parties to the General Shareholders Agreement, or their Related Parties, with the Shareholders undertaking at the outset to sign an amendment to the General Shareholders Agreement on the Cut-Off Date so as to reflect the provisions of this Clause 25.6. For the avoidance of doubt, there will be no adjustment to the percentages of the special quorums of the General Shareholders Meeting as a result of sales or reduction of the equity interest of the Shareholders AG TELECOM, LF TEL, FATL, BRATEL BRASIL, BNDESPAR, PREVI, PETROS and FUNCEF carried out or having taken place after the Cut-Off Date.

25.7 The Shareholders and the Company declare they are aware of the contents of the Temporary Voting Agreement of the Shareholders of Oi S.A. and of Telemar Participações S.A. (to be referred to as “Corpco”) between Caravelas Fundo de Investimento em Ações, Portugal Telecom SGPS S.A., Bratel Brasil S.A., Telemar Participações S.A., Andrade Gutierrez S.A. and Jereissati Telecom S.A. entered into on February 19, 2014 and amended on September 3, 2014, such document being filed at the head offices of Oi and recorded in the respective share ownership registries”.

CLAUSE TWO – GENERAL PROVISIONS

2.1 Capitalized terms not expressly defined in this 3^rd Amendment shall have the meaning attributed to them in the General Shareholders Agreement and the 1^st and 2^nd Amendments.

2.2 All other terms and conditions of the General Shareholders Agreement remain in force and are hereby ratified by the Shareholders.

2.3 This 3^rd Amendment shall be irrevocable and irreversible for the undersigned parties and their respective successors under any title.

IN WITNESS WHEREOF, the Parties have executed this instrument in 12 (twelve) counterparts of equal form and content in the presence of the 2 (two) undersigned witness.

6

The pages of this instrument were initialed by Érika Araújo Taccola, attorney for the BNDES System, with authorization from the legal representatives, undersigned.

Rio de Janeiro, September 8, 2014.

(Signature pages to follow)

7

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 1/11

AG TELECOM PARTICIPAÇÕES S.A.

ANDRADE GUTIERREZ S.A.

8

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 2/11

BNDES PARTICIPAÇÕES S.A. – BNDESPAR

9

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 3/11

CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI

10

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 4/11

FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL.

11

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 5/11

FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF

12

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 6/11

FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS

13

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 7/11

BRATEL BRASIL S.A.

14

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 8/11

LF TEL S.A.

JEREISSATI TELECOM S.A.

15

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 9/11

PORTUGAL TELECOM SGPS S.A.

16

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 10/11

TELEMAR PARTICIPAÇÕES S.A.

17

3^RD AMENDMENT TO THE SHAREHOLDERS AGREEMENT OF TELEMAR PARTICIPAÇÕES S.A., EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ, S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 11/11

18

Exhibit 99.14

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original document was prepared in Portuguese and in case of any divergence, discrepancy or difference between this version and the Portuguese version, the Portuguese version shall prevail. The Portuguese version is the only valid and complete version and shall prevail for any and all purposes. There is no assurance as to the accuracy, reliability or completeness of the translation. Any person reading this translation and relying on it should do so at his or her own risk.

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT EXECUTED ON FEBRUARY 19, 2014

BETWEEN

AG TELECOM PARTICIPAÇÕES S.A.

ANDRADE GUTIERREZ S.A.

BNDES PARTICIPAÇÕES S.A. – BNDESPAR

CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI

FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL

FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF

FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS

LF TEL S.A

JEREISSATI TELECOM S.A.

BRATEL BRASIL S.A.

AND, AS INTERVENING PARTIES,

TELEMAR PARTICIPAÇÕES S.A.

PORTUGAL TELECOM, SGPS S.A.

EXECUTED ON SEPTEMBER 8, 2014

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT EXECUTED ON APRIL 25, 2008 AND AMENDED ON JANUARY 25, 2011.

By this instrument:

2

individually also referred to as a “Party” or “Shareholder” and collectively referred to as the “Parties” or “Shareholders”, and, further,

as “Intervening Parties”,

3

WHEREAS:

The PARTIES have agreed to enter into this 1^st Amendment to the Termination of the Telemar Participações S.A. Shareholders Agreement executed on April 25, 2008 and amended on January 25, 2011 (the “1^st Amendment”), which shall be governed by the following terms and conditions:

CLAUSE ONE – AMENDMENT OF CLAUSE TWO

1.1. The Shareholders agree to amend Clause Two of the Termination, which governs the condition precedent to the effectiveness of said Termination, to remove the reference to the Merger of Portugal Telecom by Corpco, as a result of which Clause Two shall now read as follows:

“CLAUSE TWO – EFFICACY

2.1. This Termination is signed under the condition subsequent set forth in Article 125 et seq. of the Civil Code and shall only be effective following the actual implementation of the Merger of the Oi Shares by Corpco.”

4

CLAUSE TWO – GENERAL PROVISIONS

2.1. Capitalized terms not expressly defined in this 1^st Amendment shall have the meaning attributed to them in the Termination.

IN WITNESS WHEREOF, the Parties have executed this instrument in 12 (twelve) counterparts of equal form and content in the presence of the 2 (two) undersigned witness.

The pages of this instrument were initialed by Érika Araújo Taccola, attorney for the BNDES System, with authorization from the legal representatives, undersigned.

Rio de Janeiro, September 8, 2014.

(Signature pages to follow)

5

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 1/11

AG TELECOM PARTICIPAÇÕES S.A.

ANDRADE GUTIERREZ S.A.

6

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 2/11

BNDES PARTICIPAÇÕES S.A. – BNDESPAR

7

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 3/11

CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI

8

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 4/11

FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL

9

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 5/11

FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF

10

1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 6/11

FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS

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1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 7/11

BRATEL BRASIL S.A.

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1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 8/11

LF TEL S.A.

JEREISSATI TELECOM S.A.

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1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 9/11

PORTUGAL TELECOM SGPS S.A.

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1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 10/11

TELEMAR PARTICIPAÇÕES S.A.

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1^ST AMENDMENT TO THE TERMINATION OF THE TELEMAR PARTICIPAÇÕES S.A. SHAREHOLDERS AGREEMENT, EXECUTED BETWEEN BNDES PARTICIPAÇÕES S.A. – BNDESPAR, CAIXA DE PREVIDÊNCIA DOS FUNCIONÁRIOS DO BANCO DO BRASIL – PREVI, AG TELECOM PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., LF TEL S.A., JEREISSATI TELECOM S.A., FUNDAÇÃO ATLÂNTICO DE SEGURIDADE SOCIAL, FUNDAÇÃO DOS ECONOMIÁRIOS FEDERAIS – FUNCEF, FUNDAÇÃO PETROBRAS DE SEGURIDADE SOCIAL – PETROS, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A. AND PORTUGAL TELECOM, SGPS S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 11/11

Witnesses:

16

Exhibit 99.16

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original document was prepared in Portuguese and in case of any divergence, discrepancy or difference between this version and the Portuguese version, the Portuguese version shall prevail. The Portuguese version is the only valid and complete version and shall prevail for any and all purposes. There is no assurance as to the accuracy, reliability or completeness of the translation. Any person reading this translation and relying on it should do so at his or her own risk.

1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A.

AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”) EXECUTED ON FEBRUARY 19, 2014

BETWEEN

PORTUGAL TELECOM, SGPS S.A.

CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES

BRATEL BRASIL S.A.

TELEMAR PARTICIPAÇÕES S.A.

ANDRADE GUTIERREZ S.A.

JEREISSATI TELECOM S.A.

AND, AS INTERVENING PARTY

OI S.A.

EXECUTED ON SEPTEMBER 8, 2014.

1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND CORPCO EXECUTED FEBRUARY 19, 2014

By this instrument:

Individually also referred to as a “Party” and jointly referred to as the “Parties”,

2

And, as “Intervening Party”,

WHEREAS:

The PARTIES have agreed to enter into this 1^st Amendment to the Temporary Voting Agreement of the Shareholders of Oi S.A. and Corpco (the “1^st Amendment”), under the terms and for the purposes of article 118 of Law 6.404, of December 15, 1976 (the “Corporation Law”), as amended, which shall be governed by the following clauses and conditions:

CLAUSE I – AMENDMENT OF CLAUSE TWO

1.1 The parties agree to amend Clause Two of the Temporary Voting Agreement which governs the General Meetings of Oi and Corpco, to change the deadlines established therein to remove references to the Merger of Portugal Telecom into Corpco, as a result of which Clause Two shall now read as follows:

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“CLAUSE II – GENERAL MEETINGS OF OI AND CORPCO SHAREHOLDERS

2.1 The Shareholders, irrevocably and irreversibly, hereby undertake to perform all necessary acts and to cooperate with the performance of all necessary acts by the other Parties and by Oi for the accomplishment of (i) the Merger of BRATEL BRASIL into Oi; and (ii) the Merger of Oi Shares by Corpco, including the approval of Oi financial statements.

2.2 Subject to the provisions of the Clauses below, the Shareholders and Oi shall call, and shall cause Oi to call, on 02/28/2015 at the latest, an Extraordinary General Meeting of Oi shareholders (“AGE Date”), in order to decide about the Merger of BRATEL BRASIL into Oi and the Merger of Oi Shares by Corpco (the “Oi AGE”), including but not limited to: (i) the ratification of the appointment and hiring of the appraiser company responsible for the drafting of the valuation reports for the purposes of the Merger of BRATEL BRASIL into Oi and the Merger of Oi Shares by Corpco (the “Appraisal Reports”); (ii) the approval of the Valuation Reports; (iii) the approval of the agreement governing the Merger of BRATEL BRASIL into Oi and the Merger of Oi Shares by Corpco, which draft constitutes Exhibit 2.2 of this Agreement; (iv) the approval of the Merger of BRATEL BRASIL into Oi and the Merger of Oi Shares by Corpco, under the terms and conditions of the respective agreements referred to in item “iii” above; and (v) the performance, by Oi management, of the necessary acts for the implementation of the Merger of BRATEL BRASIL into Oi and the Merger of Oi Shares by Corpco.

2.2.1 The Shareholders, irrevocably and irreversibly, hereby undertake to (i) attend the Oi AGE; (ii) cause the members of the Oi Board of Directors designated by them to attend the Oi Board of Directors meeting that will decide on the Merger of BRATEL BRASIL into Oi and the Merger of Oi Shares by Corpco (the “Oi RCA”); and (iii) vote and cause the members of Oi Board of Directors designated by them to vote, at the Oi AGE as well as the Oi RCA, favorably for the approval, without reservations, exceptions or restrictions, of the Merger of BRATEL BRASIL into Oi and the Merger of Oi Shares by Corpco.

2.2.2 Considering that the merger of Portugal Telecom SGPS by Corpco will no longer be implemented within the scope of the Transaction, the Shareholders nevertheless undertake to continue pursuing the objective of integrating the shareholder bases of Oi and Portugal Telecom SGPS.

2.3 In the event that, during the term of this Temporary Voting Agreement, any legal, arbitral or administrative remedy is determined, even if of a preliminary nature, in such a manner that the Oi AGE and/or the Oi RCA and/or the Corpco AGE and/or the Corpco RCA cannot be held, or so that the effects of the approval of the Merger of BRATEL BRASIL into Oi and/or the Merger of Oi Shares by are suspended, or, in any manner so, that the effect or the scope of the Merger of BRATEL BRASIL into Oi and/or the Merger of Oi Shares by Corpco are affected or restricted, each one of the Shareholders hereby irrevocably and irreversibly agrees to take and cause Oi to take all necessary measures to distance itself and implement, as soon as possible, the effects of the legal, arbitral or administrative remedies mentioned.

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2.4 The Chair of the Oi AGE, the Oi RCA, the Corpco AGE and the Corpco RCA shall refrain from registering and calculating the votes cast in disagreement with this Temporary Voting Agreement, subject to the provisions by article 118, § 8 of Corporation Law.

2.5 The Shareholders hereby, further irrevocably and irreversibly undertake to exercise their voting rights in order to maintain the ordinary course of Oi’s business during the term of this Temporary Voting Agreement, refrain from taking any measure or practice any act that affects or limits the effects or the scope of this instrument. For the purposes of this Clause 2.5, it is considered the ordinary course of business the activities which, by their nature, purpose or manner of execution, are necessary for the achievement of Oi’s corporate purposes, considering the maintenance of its business at current levels, consistent with the past practices and guidelines determined by the corporate bodies and without any kind of interruption or delay.

2.5.1 The Shareholders hereby, further, irrevocably and irreversibly undertake to keep the members of the Oi Board of Directors in their current positions on the date of the execution of this Temporary Voting Agreement, instructing them to maintain the ordinary course of business of Oi. In case of vacancy or resignation of any member of the Oi Board of Directors during the term of this Temporary Voting Agreement, the election of the substitute shall be made by Telemar Participações according to the rules provided in its Shareholders Agreement in force on this date for the election of the members of the Board of Directors.”

CLAUSE II – MODIFICATION OF CLAUSE III

2.1 The Parties agree to amend Clause III of the Temporary Voting Agreement, which governs the prohibition to transfer and encumber Affected Shares, so as to exclude from its scope the Exchange Agreement executed by Portugal Telecom SGPS on this date, as a result of which Clause Two shall now read as follows:

“CLAUSE III – PROHIBITION TO TRANSFER AND ENCUMBER AFFECTED SHARES

3.1 During the term of this Temporary Voting Agreement, the Shareholders irrevocably and irreversibly undertake not to sell, dispose or transfer, directly or indirectly, by any means or manner, their Affected Shares, or any rights related to these Affected Shares, as well as not to create encumbrances or liens of any nature, judicial or extra-judicial, on the Affected Shares, including but not limited to pledge, bond, usufruct, chattel mortgage, trust, execution of purchase and sale or purchase option commitment, right of first refusal, lease, as well as the execution of other shareholders agreements.

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3.1.1 The provisions in the introductory paragraph of this Clause do not apply to the “Exchange Agreement, and Other Covenants” (Contrato de Permuta e Outras Avenças) to be entered into on September 8, 2014 between Portugal Telecom SGPS and PT Internacional Finance B.V., PT Portugal, SGPS S.A., Oi, and Telemar Participações, in respect of 474,348,720 (four hundred seventy-four million, three hundred forty-eight thousand, seven hundred twenty) common shares and 948,697,440 (nine hundred forty-eight million, six hundred ninety-seven thousand, four hundred forty) preferred shares of Oi.”

CLAUSE II – MODIFICATION OF CLAUSE VII

2.1 The Parties agree to amend paragraph 7.2 of Clause VII of the Temporary Voting Agreement, which governs the effectiveness and the term of the Temporary Voting Agreement, so as to exclude reference to the Merger of Portugal Telecom into Corpco and to modify the term established therein, as a result of which paragraph 7.2 of Clause VII shall now read as follows:

“CLAUSE VII – EFFECTIVENESS AND TERM

7.2 This Temporary Voting Agreement shall remain in force until (i) the consummation of the Merger of Oi Shares into Corpco; or (ii) March 31, 2015, whichever occurs first.”

CLAUSE III – GENERAL PROVISIONS

3.1 Capitalized terms not expressly defined in this 1^st Amendment shall have the meaning attributed to them in the Temporary Voting Agreement.

3.2 All further terms and conditions of the Temporary Voting Agreement shall remain in effective and hereby ratified by the Parties.

3.3 The terms and conditions of the 1^st Amendment shall benefit and irrevocably and irreversibly bind the undersigned and their respective successors, including but not limited to the successors of the Shareholders following the Restructuring of Telemar Participações.

IN WITNESS HEREOF, the Parties executed this instrument in 7 (seven) counterparts of the same content and form, before the 2 (two) undersigned witnesses.

Rio de Janeiro, September 8, 2014.

(Signature pages to follow)

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1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”), ENTERED INTO BETWEEN PORTUGAL TELECOM, SGPS S.A., CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., JEREISSATI TELECOM S.A. AND OI S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 1/8

PORTUGAL TELECOM, SGPS S.A.

7

1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”), ENTERED INTO BETWEEN PORTUGAL TELECOM, SGPS S.A., CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., JEREISSATI TELECOM S.A. AND OI S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 2/8

CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES

Managed by BTG Pactual Serviços Financeiros S.A. DTVM

8

1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”), ENTERED INTO BETWEEN PORTUGAL TELECOM, SGPS S.A., CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., JEREISSATI TELECOM S.A. AND OI S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 3/8

BRATEL BRASIL S.A.

9

1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”), ENTERED INTO BETWEEN PORTUGAL TELECOM, SGPS S.A., CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., JEREISSATI TELECOM S.A. AND OI S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 4/8

TELEMAR PARTICIPAÇÕES S.A.

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1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”), ENTERED INTO BETWEEN PORTUGAL TELECOM, SGPS S.A., CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., JEREISSATI TELECOM S.A. AND OI S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 5/8

ANDRADE GUTIERREZ S.A.

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1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”), ENTERED INTO BETWEEN PORTUGAL TELECOM, SGPS S.A., CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., JEREISSATI TELECOM S.A. AND OI S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 6/8

JEREISSATI TELECOM S.A.

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1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”), ENTERED INTO BETWEEN PORTUGAL TELECOM, SGPS S.A., CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., JEREISSATI TELECOM S.A. AND OI S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 7/8

OI S.A.

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1^ST AMENDMENT TO THE TEMPORARY VOTING AGREEMENT OF THE SHAREHOLDERS OF OI S.A. AND TELEMAR PARTICIPAÇÕES S.A. (TO BE REFERRED TO AS “CORPCO”), ENTERED INTO BETWEEN PORTUGAL TELECOM, SGPS S.A., CARAVELAS FUNDO DE INVESTIMENTO EM AÇÕES, BRATEL BRASIL S.A., TELEMAR PARTICIPAÇÕES S.A., ANDRADE GUTIERREZ S.A., JEREISSATI TELECOM S.A. AND OI S.A. ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 8/8

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Exhibit 99.17

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original document was prepared in Portuguese, and in case of any divergence, discrepancy or difference between this version and the Portuguese version, the Portuguese version shall prevail. The Portuguese version is the only valid and complete version and shall prevail for any and all purposes. There is no assurance as to the accuracy, reliability or completeness of the translation. Any person reading this translation and relying on it should do so at his or her own risk.

EXCHANGE AGREEMENT, AND OTHER COVENANTS

AMONG

PORTUGAL TELECOM INTERNATIONAL FINANCE B.V.

PT PORTUGAL SGPS, S.A.

AND

PORTUGAL TELECOM, SGPS S.A.

AND, FURTHER,

OI S.A.

AND

TELEMAR PARTICIPAÇÕES S.A.

DATED SEPTEMBER 8, 2014.

EXCHANGE AGREEMENT, AND OTHER COVENANTS

By this instrument, the parties:

on the one side,

1. PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., a company incorporated under and governed by the laws of the Netherlands, headquartered in Amsterdam, the Netherlands, and with principal offices in Naritaweg 165, 1043 BW Amsterdam, the Netherlands, registered with the Amsterdam Chamber of Commerce under n.º 34108060, duly represented for the purposes hereof pursuant to its Bylaws (“PT Finance”);

2. PT PORTUGAL SGPS, S.A., a Portuguese corporation (sociedade anónima), headquartered at Avenida Fontes Pereira de Melo, n.º 40, in the district of São Jorge de Arroios, Lisbon, registered as a legal entity under n.º 507690737, with a capital stock of EUR 3,450,000,000.00 (three billion four hundred and fifty million Euros), duly represented for the purposes hereof pursuant to its Bylaws (“PT Holding”);

and on the other,

3. PORTUGAL TELECOM, SGPS S.A., a publicly held corporation governed by Portuguese law (sociedade aberta de direito português), headquartered at Avenida Fontes Pereira de Melo, n.º 40, in the district of São Jorge de Arroios, Lisbon, registered as a legal entity under n.º 503215058, with a capital stock of EUR 26,895,375 (twenty-six million, eight hundred ninety-five thousand, three hundred seventy-five Euros), duly represented for the purposes hereof pursuant to its Bylaws (“PT SGPS”);¹

and, further,

4. OI S.A., a Brazilian corporation (sociedade por ações) headquartered in the City and State of Rio de Janeiro, at Rua do Lavradio nº. 71, 2^nd floor, Center, registered with the CNPJ/MF under n°. 76.535.764/0001-43, duly represented for the purposes hereof pursuant to its Bylaws (“Oi”); and

5. TELEMAR PARTICIPAÇÕES S.A., a publicly held company (companhia aberta) headquartered at Praia de Botafogo nº. 300, 11^th floor, room 1101 (part), Botafogo, City of Rio de Janeiro, RJ, registered with the CNPJ/MF under n.º 02.107.946/0001-87, duly represented for the purposes hereof pursuant to its Bylaws (“Telemar Participações” or “CorpCo”);

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the parties described above shall also be referred to herein, individually, a “Party,” or together, the “Parties;” and

WHEREAS:

(i) On July 15, 2014, Oi and PT SGPS executed a Memorandum of Understanding (the “MOU”) establishing the principles, terms and conditions for the adjustments needed to fully implement the ongoing transaction involving the combination of the activities and businesses of PT SGPS and Oi;

(ii) As one of the steps in such business combination, on May 5, 2014, PT SGPS contributed all of its operational activities, through the subscription for shares issued by Oi through the contribution of all of the shares issued by PT Holding in the context of Oi’s capital increase on April 28, 2014 (the “Oi Capital Increase”);

(iii) As described in the MOU, PT SGPS, PT Finance and PT Holding intend to exchange 474,348,720 (four hundred seventy-four million, three hundred forty-eight thousand, seven hundred and twenty) common shares (“AON”) and 948,697,440 (nine hundred and forty-eight million, six hundred ninety-seven thousand, four hundred and forty) preferred shares issued by Oi (“APN” and, together with the AON, the “Exchange Shares”), all free and clear of any and all liens, claims, options, rights of preference, charges and any other encumbrances of a judicial or extrajudicial nature (“Encumbrances”), held directly by PT SGPS, for securities issued by Rio Forte Investments, S.A. (“Rio Forte”) in the total principal amount of €897,000,000.00 (eight hundred ninety-seven million Euros) (the “Securities”), held by PT Finance and PT Holding, which Securities were contributed to Oi in the context of the Oi Capital Increase (“Exchange Assets” and “Exchange”, respectively), under the terms and conditions established in this instrument;

the Parties RESOLVE to execute this Exchange Agreement, and Other Covenants (the “Agreement”), which will be governed by the provisions described below:

CLAUSE 1

EXCHANGE

1.1 Exchange. Subject to satisfaction of the Condition Precedent and the other terms and conditions established in this Agreement, PT Finance, PT Holding and PT SGPS undertake to effect, at the Closing Date, the Exchange, irrevocably and irreversibly, without return, of the Exchange Shares held by PT SGPS for the Securities held by PT Finance and PT Holding, in which:

(i) PT Finance shall transfer Securities and all the rights associated therewith that it holds in the total principal amount of €697,000,000.00 (six hundred ninety-seven million Euros) to PT SGPS and, in exchange, shall receive 368,585,349 AONs and 737,170,698 APNs, free and clear of any Encumbrance; and

(ii) PT Holding shall transfer Securities and all the rights associated therewith that it holds in the total principal amount of €200,000,000.00 (two hundred million Euros) to PT SGPS and, in exchange, shall receive 105,763,371 AONs and 211,526,742 APNs, free and clear of any Encumbrance.

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1.2 Transfer of the Exchange Assets. Subject to satisfaction of the Condition Precedent and the other terms and conditions established in this Agreement, PT SGPS, PT Finance, PT Holding and Oi hereby undertake to perform, on the Closing Date, all actions needed to record the transfer (i) of the Exchange Shares to PT Finance and PT Holding and (ii) of the Securities to PT SGPS, as described in Clause 1.1 above.

1.2.2 Notwithstanding anything to the contrary in Clause 1.2.1 above, Oi, PT Finance and PT Holding shall cooperate and provide all the documentary support requested by PT SGPS for taking all measures necessary to collect on the credits represented by the Securities.

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CLAUSE 2

CONDITION PRECEDENT AND CLOSING

2.1. Condition Precedent. The Parties acknowledge that they shall only be bound to proceed with the Closing (as defined in Clause 2.2 below) if the authorization of the Comissão de Valores Mobiliários (“CVM”) is duly obtained for (a) the receipt of the Exchange Shares by PT Finance and PT Holding; (b) the maintenance in treasury of shares issued by Oi (and, after the merger of Oi shares into CorpCo, by CorpCo), in a volume equivalent to the maximum number of Exchange Shares; and (c) the grant of the call option by Oi, PT Finance, PT Holding and CorpCo in favor of PT SGPS, in a volume equivalent to the maximum number of Exchange Shares, in accordance with the terms of the Call Option Agreement and Other Covenants executed by Oi, PT Finance, PT Holding, CorpCo and PT SGPS on the date hereof (the “Condition Precedent”).

2.1.1 If the Condition Precedent is not satisfied by March 31, 2015, no Party shall have any obligation to proceed with the Closing, under the terms set forth herein, and any of the Parties shall have the right to, at its exclusive discretion, unilaterally terminate this Agreement, and all of its terms and conditions, by means of written notice sent to the other Parties in this regard, in observance of Clause 8.1 below.

2.2 Closing. Within 3 (three) business days as from the date on which the Condition Precedent is satisfied, the Parties shall effect the Exchange pursuant to Clause 1 (the “Closing”). The date on which the Exchange is effected is hereinafter referred to as the “Closing Date.”

CLAUSE 3

REPRESENTATIONS AND WARRANTIES

3.1 Representations and Warranties of PT SGPS. PT SGPS hereby represents and warrants to Oi, PT Finance, PT Holding and CorpCo that (i) PT SGPS is on the date hereof and shall be on the Closing Date, the sole and legitimate owner and holder of all of the Exchange Shares, and all that they represent; (ii) the Exchange Shares are free and clear of any Encumbrance or restriction of any nature that would impede or limit their alienation, except as provided in the Shareholders’ Agreements for Oi and CorpCo filed at the headquarters of such companies; and (iii) PT SGPS has obtained all the authorizations needed to execute this Agreement, including approval of the transactions provided for in this Agreement by the Board of Directors of PT SGPS and, thereafter, by the general shareholders’ meeting of PT SGPS.

3.2 Oi’s Representations and Warranties. Oi, PT Finance, PT Holding and CorpCo hereby represent and warrant to PT SGPS that Oi, CorpCo, PT Finance and PT Holding have obtained all the approvals needed to execute this Agreement, including (i) the

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approval, with Bratel Brasil S.A.’s abstention from the vote, of the transactions provided for in this Agreement at a prior meeting (reunião prévia) of the shareholders of Telemar Participações, under the terms of the Telemar Participações Shareholders’ Agreement executed by Andrade Gutierrez S.A., BNDES Participações S.A. – BNDESPAR, Caixa de Previdência dos Funcionários do Banco do Brasil – PREVI, Fundação Atlântico de Seguridade Social, Fundação dos Economiários Federais – FUNCEF, Fundação Petrobras de Seguridade Social – PETROS, LF Tel, Bratel Brasil, Telemar Participações and PT SGPS, dated April 25, 2008, as amended on January 25, 2011 and on February 19, 2014 (the “Telemar Participações Shareholders’ Agreement”); and (ii) the approval of the transactions provided for in this Agreement by the Board of Directors of Oi.

3.2.1 For the avoidance of doubt, Oi, PT Finance and PT Holding shall take no responsibility, in any way or by any means, or at any time, for the existence, formalization, validity, solvency of the issuer, any guarantors, or even for the existence of liens, restrictions or any other Encumbrances on the Securities either existing prior to or on the date of their contribution to Oi’s capital stock, or at any time, including after such date, except the Encumbrances voluntarily constituted by PT Finance or PT Holding as from July 15, 2014, and no responsibility stemming, directly or indirectly, from holding and preserving the Securities, or from transferring such Securities pursuant to the Exchange, shall be imputed to them.

CLAUSE 4

INDEMNIFICATION

4.1 Indemnification by PT SGPS. If PT SGPS breaches any of its representations, warranties, commitments or obligations as established in this Agreement, PT SGPS agrees to indemnify, defend and hold Oi, PT Finance, PT Holding and/or CorpCo harmless against any damages or restrictions of rights suffered by them, resulting or arising from such breach. Without limiting the provisions of Clause 5 below, and subject to Closing, PT SGPS shall further hold Oi, PT Finance, PT Holding and/or CorpCo harmless and defend them against any loss (including costs, interest and penalties, as well as reasonable legal fees) or liability (together, “Loss”) of any kind arising, directly or indirectly, from holding the Securities and their transfer pursuant to the Exchange.

4.2 Indemnification by Oi, PT Finance, PT Holding and CorpCo. If Oi, PT Finance, PT Holding and/or CorpCo breach any of their respective representations, warranties, commitments or obligations as established in this Agreement, Oi, PT Finance, PT Holding and/or CorpCo agree to indemnify, defend and hold PT SGPS harmless against any damages or restrictions of rights suffered by PT SGPS, resulting or arising from such breach. Subject to Closing, Oi and CorpCo shall further hold PT SGPS harmless and defend it against any Loss of any kind arising, directly or indirectly, from PT SGPS’s contingent or absolute tax or anti-trust obligations in relation to the assets contributed in the Oi Capital Increase and from PT SGPS’s management activities, with reference to acts

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or triggering events occurring on or prior to May 5, 2014, including those disclosed in the data room in preparation for the Global Offering, reported in the Global Offering documentation, including the obligations contemplated by or arising from the agreements referred to in the Global Offering documentation, but expressly excluding any obligation to indemnify for any Losses incurred by PT SGPS as a result of the financial investments in the Securities and the acquisition of the Securities pursuant to the Exchange.

4.3 Indemnification Procedure. For the purposes of this Clause 4, the Party claiming indemnification for Losses (the “Indemnifiable Party”), including due to a claim issued by a governmental authority or a third party that could constitute an indemnifiable Loss (a “Third-Party Claim”), shall notify in writing the Party responsible for the indemnification (the “Indemnifying Party”) with respect to such claim or Third-Party Claim. In the event of a Third-Party Claim, the notice shall be given within the first 1/3 (third) of the legal period for presenting a defense or possible motion against such claim (“Defense”), provided however that if the legal period for Defense is 5 (five) days or less, such notice shall be given within the first half of the legal period for the Defense. The Indemnifying Party shall assume the Defense of the Third-Party Claim, appointing lawyers of its choice, bearing all the costs arising therefrom, and shall provide the necessary guarantees (or shall replace any such guarantee already provided by the Indemnifiable Party) to present or assume the Defense. The Indemnifiable Party shall provide such information and documents as the Indemnifying Party reasonably requests for conducting the Defense. The Indemnifiable Party shall also have the right monitor the progress of the Third-Party Claim, at its own expense and cost, and such Indemnifiable Party shall also be entitled to appoint its own counsel to accompany the defense conducted by the Indemnifying Party. Subject to Closing, the Indemnifying Party shall immediately assume the defense of any Third-Party Claims brought against the Indemnified Party that could generate Losses for which the Indemnifying Party is responsible in accordance with this Clause 4, and the Indemnifying Party shall assume the related costs and arrange for the replacement of any guarantees provided hitherto by the Indemnified Party in the context of the applicable Defense. The indemnification for Losses provided for in this Clause shall be paid within 10 (ten) days of the receipt by the Indemnifying Party of the notice from the Indemnifiable Party of the documents evidencing the Loss incurred, including from any final decision, not subject to appeal, relating to the Loss, as applicable.

CLAUSE 5

RELEASE

5.1 Release. Subject to the Closing, in the form set forth herein, PT Finance, PT Holding, CorpCo and Oi grant a, upon completion of the Exchange, full, irreducible, general and irrevocable release to PT SGPS, and to the administrators of PT SGPS, in relation to the making of the financial investments in the Securities and their subsequent contribution to Oi in the context of the Oi Capital Increase, acknowledging that they have

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nothing to claim in the present, past or future in this respect, on any grounds, including omissions or incomplete information relating specifically to the Securities, their situation and the risks involved, subject only to the provisions of Clause 5.2.1.

5.2 Waiver of PT Finance, PT Holding, CorpCo and Oi. Subject to the Closing and notwithstanding the provisions of Clause 8.4, PT Finance, PT Holding, CorpCo and Oi expressly and definitively waive any right to suit, claim, annulment, specific performance, of giving, doing or not doing, redress or indemnification (with the express and exclusive exception of the right of recourse against PT SGPS under the terms of Clause 5.2.1 below), before any jurisdiction, arbitral tribunal or in the context of any other proceeding, by reason of any acts, facts, omissions or matters relating exclusively to the making of the financial investments in the Securities and of their contribution to Oi’s share capital, as well as by reason of representations, warranties, information or omissions of information (or, generally, relating to the adequacy and completeness of the information disclosed), relating specifically to the Securities, their situation and the risks involved.

5.2.1 The release and the waiver granted in Clauses 5.1 and 5.2 above shall not impair the right of recourse (direito de regresso) of PT Finance, PT Holding, CorpCo or Oi against PT SGPS. If any judicial, arbitral or administrative action of any nature is brought against PT Finance, PT Holding, CorpCo or Oi in connection with the making of the financial investments in the Securities and their contribution to Oi’s share capital, as well as in connection with any representations, warranties, information or omissions of information (or, generally, relating to the adequacy and completeness of the information disclosed), PT Finance, PT Holding, CorpCo and Oi undertake to immediately inform PT SGPS thereof and to defend again any such proceedings in a diligent manner. PT SGPS, should it so desire, may, at its own expense, appoint a lawyer to monitor the proceeding. The defenses of Oi, CorpCo, PT Finance and/or PT Holding, in such proceedings, shall not contain an impleader (denunciação da lide). Accordingly, the parties acknowledge that the absence of a presentation of an impleader in such proceedings shall not preclude PT Finance, PT Holding, Oi and/or CorpCo from pursuing the related rights of recourse against PT SGPS, to litigate the right of recourse to recover the total amount of any adverse awards or decisions, costs and expenses any of them incur, after any adverse awards or decisions in such proceedings become final and not subject to appeal. For the avoidance of doubt, except only for any measure required to suspend the judicial or extrajudicial statute of limitations, no other measure of recourse shall be taken before such adverse decisions are final and not subject to appeal.

5.2.2 For the avoidance of doubt, the waiver granted in Clause 5.2 covers any action or claim against PT SGPS and its administrators.

5.3 Release. Subject to Closing, in the form set forth herein, PT SGPS grants a full, irreducible, general and irrevocable release to PT Finance, PT Holding, Oi and CorpCo,

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and to their respective administrators, in relation to the transfer of the Securities pursuant to the Exchange that is the subject of this Agreement, acknowledging that it has nothing to claim in the present, past or future on any grounds in that respect.

CLAUSE 6

RESCISSION

6.1 This Agreement shall be automatically rescinded, without need of judicial or extrajudicial notice, only in the case where there is a final judicial decision, not subject to appeal, that would prevent the Closing.

CLAUSE 7

TERMINATION

7.1 This Agreement may be unilaterally terminated by PT SGPS and/or Oi and CorpCo if the Closing does not occur by March 31, 2015, for any reason, including, but not limited to, if the Condition Precedent is not satisfied by such date.

7.2 Without prejudice to the exercise of all legal measures to which they are entitled, if the Closing fails to occur due to an act or omission by one of the Parties, the innocent Party may at its discretion claim specific performance of the obligation left unfulfilled by the other Party and, consequently, consummation of the Closing.

7.3 If a judicial, arbitral or administrative order that hinders the performance of this Agreement is handed down, the Parties undertake to, in good faith, and at their respective expense, take all measures to protect the Agreement and its performance in accordance with its terms, toward eliminating, in the shortest possible period, all the effects of such order.

7.3.1 Once the effects of the judicial, arbitral or administrative order have been eliminated, the Parties shall fulfill in full their obligations as set forth in this Agreement, without suspension or alteration, in faithful observance of the periods set forth contractually.

7.4 The provisions regarding conflict resolution set forth in Clause 9 shall survive termination of this Agreement.

CLAUSE 8

MISCELLANEOUS

8.1 Any communication, notice or subpoena relating to this Agreement, including notice of arbitration, shall be deemed delivered when received by the other Party (i) by

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registered mail, through a reputable courier company, at the time of effective receipt at the address(es) indicated below, (ii) at the time delivered, if delivered by hand, or (iii) on the date of confirmation of receipt of transmission issued by a fax machine, when faxed, as applicable, to the addresses and telephone/fax numbers shown below (or any other address or telephone/fax number as may be indicated by a Party, in writing, to the other Parties):

To Oi, PT Finance or PT Holding:

Attention: Bayard De Paoli Gontijo

Address: Rua Humberto de Campos, n.º 425, 8º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-2972

Fax: +55 21 3131-1155

Flavio Nicolay Guimarães

Address: Rua Humberto de Campos, n.º 425, 7º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-2227

Fax: +55 21 3131-1383

With copy to:

Eurico de Jesus Teles Neto

Address: Rua Humberto de Campos, n.º 425, 8º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-1207

Fax: +55 21 3131-1155

To PT SGPS:

Attention: Secretaria Geral

Avenida Fontes Pereira de Melo nº. 40, freguesia de São Jorge de Arroios,

Concelho de Lisboa, Portugal

To Telemar Participações:

Attention: Sr. Fernando Magalhães Portella

Praia de Botafogo nº. 300, sala 1101, Botafogo, Rio de Janeiro, RJ, Brasil

8.1.1 Any Party may change the address to which notice shall be sent by written notice to the other contracting Parties in accordance with this Clause 8, it being however specified that for the purposes of this provision, the notice shall be deemed to have been received only upon acknowledgement of receipt by each of the other Parties.

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8.2 The main purpose of this Agreement is to establish the terms and conditions of a common agreement between the Parties, and in no circumstance shall it be interpreted as an acknowledgment of any act, measure or omission, by either of the Parties or any of their administrators which may be deemed contrary to applicable law or any contractual obligation.

8.3 This Agreement contains the entire agreement and understanding in respect of the object of this instrument among the contracting Parties, and specifically replaces any prior understanding of the Parties regarding the object of this instrument, except for the Share Subscription Agreement signed on February 19, 2014.

8.4 The Parties expressly agree that, for so long as this Agreement is in effect, and until the Closing or until this Agreement is rescinded or terminated, as applicable, no Party shall bring any judicial, extrajudicial or arbitral measure in any jurisdiction at any time against the other Party or any of its administrators (both current and in office at the time of the relevant events) in relation to the Oi Capital Increase, the Share Subscription Agreement signed on February 19, 2014, the transfer of the Securities in the context of such Oi Capital Increase, and/or the Securities other than actions required to maintain and preserve their respective rights.

8.5 Prior to and as a condition to the execution of this Agreement, the following were approved at a prior meeting (reunião prévia) of the shareholders of CorpCo, pursuant to the terms of the Telemar Participações Shareholders’ Agreement (i) if feasible, the listing of CorpCo on the Bovespa, the NYSE and Euronext Lisbon, so as to allow the implementation of an alternative structure for integrating the shareholder bases of PT SGPS and CorpCo after the merger of shares of Oi into CorpCo not covered by the Exchange provided for in this Agreement; (ii) the amendment of CorpCo’s bylaws to include a limitation of 7.5% (seven and a half percent) of the voting rights applicable to (I) PT SGPS, and (II) any shareholder that, due to any future integration of the shareholder bases of CorpCo and PT SGPS, comes to hold a stake in excess of 15% (fifteen percent) of CorpCo’s total share capital, excluding the shares of CorpCo previously held by such shareholder or that come to be acquired by other means; and (iii) amendments to the deadlines and other provisions of the amendments to the shareholders’ agreements, the temporary voting agreement and the terms for termination of the shareholders’ agreements, all signed on February 19, 2014.

8.6 This Agreement may only be amended, replaced, cancelled, renewed or extended and its terms may only be waived through a written instrument signed by all Parties or, in the case of a waiver, by the Party waiving the respective right. No waiver, termination or release of this Agreement, or of any of its terms or provisions, shall be binding upon any of the contracting Parties unless confirmed in writing. Any delay in exercising a right, power or privilege provided for in this Agreement shall not be deemed a waiver of such

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right, power or recourse; nor shall the total or partial waiver of any right, power, recourse or privilege preclude any other subsequent exercise of such right, recourse, power or privilege.

8.7 This Agreement shall be binding upon and benefit the Parties and their respective permitted successors. This Agreement (and the rights and obligations provided for herein) may not be assigned by any Party without the prior written consent of the other Parties.

8.8 If any term or provision of this Agreement is declared void, invalid or ineffective, the Parties shall negotiate in good faith to replace the invalidated provisions with others that reflect, to the extent possible, their initial intentions.

8.9 The Parties shall bear their respective direct and indirect expenses incurred in connection with the negotiation and preparation of this Agreement and the consummation of the matters set forth herein.

8.9.1 Notwithstanding the other provisions in this Agreement, all taxes incident to the transactions contemplated by this Agreement and any capital gain (collectively, the “Taxes”), shall be the responsibility of the Party to which the obligation is imposed by law, and such Party shall present any and all returns and other documents relating to the Taxes for which it is responsible.

8.10 The Parties acknowledge and agree that all the terms and conditions established in this Agreement shall be subject to specific performance, as provided for in the Brazilian Code of Civil Procedure.

8.11 The Parties further acknowledge that this Agreement constitutes an extrajudicial enforcement instrument (título executivo extrajudicial), under the terms of article 585, II, of the Brazilian Code of Civil Procedure.

8.12 This Agreement as signed is irrevocable and irreversible, and constitutes legal, valid and binding obligations, which shall be binding upon and benefit, the contracting Parties and their respective successors.

8.13 The Parties undertake to respect the confidentiality of the information contained in this Agreement that qualifies as confidential information, and shall disclose the terms pertaining to the transactions that are the subject of this Agreement strictly to the extent necessary to fulfill legal or regulatory requirements to which the Parties are subject. The terms of any notice of a material fact, notice to the market or press release to be disclosed by the Parties and/or their controlled companies regarding the execution of this Agreement shall be submitted to the others in advance by each Party.

8.14 This Agreement shall be governed by and interpreted in accordance with the laws of the Federative Republic of Brazil.

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CLAUSE 9

CONFLICT RESOLUTION

9.1 The Parties shall make an effort to resolve amicably and by consensus any controversy of any nature related directly or indirectly to this Agreement involving any of the Parties (“Conflict”).

9.2 If, after discussing for a period of 10 (ten) Business Days, the Parties fail to reach an amicable solution and consensus in relation to the Conflict, then such Conflict shall be settled by arbitration, to be conducted before and administered by the Câmara de Arbitragem da Câmara de Comércio Brasil-Canadá (the “Chamber”).

9.3 The arbitration shall be conducted in accordance with the Chamber’s procedural standards in effect at the time of the arbitration.

9.4 The arbitration shall be administered by an arbitral tribunal consisting of three arbitrators, it being specified that the chair of the tribunal shall be registered with the Ordem dos Advogados do Brasil (the “Arbitral Tribunal”).

9.4.1 Each Party Involved will appoint one arbitrator. If there is more than one claimant, the claimants shall appoint a single arbitrator by mutual agreement; similarly, if there is more than one respondent, the respondents shall appoint a single arbitrator by mutual agreement. The third arbitrator, who will preside over the Arbitral Tribunal, will be selected by mutual agreement of the arbitrators appointed by the Parties Involved and/or as set forth in the regulations of the arbitral chamber.

9.4.2 Any omission, refusal, dispute, doubt and disagreement with respect to the appointment of the arbitrators by the Parties Involved or to the choice of the third arbitrator shall be settled by the Chamber.

9.4.3 The procedures provided for in this Clause shall also apply when replacing an arbitrator.

9.5 The arbitration shall take place in the City of Rio de Janeiro, in the State of Rio de Janeiro, and the Arbitral Tribunal may, with cause, decide to carry out certain specific actions in different locations.

9.5.1 The arbitration shall be conducted in Portuguese.

9.5.2 The arbitration shall follow the rules of law (de direito), applying the rules and principles of the legal system of the Federative Republic of Brazil.

9.5.3 The arbitration shall have a term of 6 (six) months, which period may be extended for cause by the Arbitral Tribunal.

9.5.4 The arbitration will be confidential.

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9.6 The Arbitral Tribunal shall allocate between the Parties, in accordance with criteria of succumbency (sucumbência), reasonability and proportionality, the payment and reimbursement of (i) any fees and other amounts due, paid or reimbursed to the Chamber, (ii) any fees and other amounts due, paid or reimbursed to the arbitrators, (iii) any fees and other amounts due, paid or reimbursed to the experts, translators, interpreters, stenographers and any other assistants as may have been appointed by the Arbitral Tribunal, (iv) any fees in succumbency and expenses of the lawyers and experts hired by the parties, to be reasonably established by the Arbitral Tribunal based on the receipts presented by the parties; (v) any reasonable travel expenses and fees of assistants or technical witnesses; and (vi) any damages for litigation in bad faith. The Arbitral Tribunal shall not condemn any of the Parties Involved to pay or reimburse contractual fees based on the success of the demand (ad exitum).

9.7 Arbitral awards shall be final and binding, neither requiring judicial ratification nor admitting any appeal, except for requests for correction (pedidos de correção) and requests for clarification to the Arbitral Tribunal as provided for under art. 30 of Law nº 9.307/96 and any annulment action based on art. 32 of Law nº 9.307/96.

9.8 Before the Arbitral Tribunal is seated, any of the Parties Involved may petition the Courts for preliminary injunctions and advance relief, although any such petition shall not affect the existence, validity and efficacy of this arbitration clause, nor represent a waiver of the obligation to submit the Conflict to arbitration. After the Arbitral Tribunal is seated, any petitions for preliminary injunctions or advance relief shall be directed to the Arbitral Tribunal.

9.9 For the purposes of (i) preliminary injunctions and advance relief before the Arbitral Tribunal is seated, (ii) enforcement of the decisions of the Arbitral Tribunal, including the final award and any partial award, (iii) any annulment action based on art. 32 of Law nº 9.307/96, and (iv) any Conflicts which, under Brazilian law cannot be settled through arbitration, the Forum of the Judicial District of Central Rio de Janeiro is elected as the sole jurisdiction, waiving all others, however special or privileged they may be.

IN WITNESS WHEREOF, the Parties cause 5 (five) originals of this Agreement, of equal substance and form, to be signed before 2 (two) witnesses.

Rio de Janeiro, September 8, 2014.

(Signature pages to follow)

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EXCHANGE AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 1/7

PORTUGAL TELECOM INTERNATIONAL FINANCE B.V.

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EXCHANGE AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 2/7

PORTUGAL TELECOM INTERNATIONAL FINANCE B.V.

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EXCHANGE AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 3/7

PORTUGAL SGPS, S.A.

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EXCHANGE AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 4/7

PORTUGAL TELECOM SGPS S.A.

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EXCHANGE AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 5/7

OI S.A.

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EXCHANGE AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 6/7

TELEMAR PARTICIPAÇÕES S.A.

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EXCHANGE AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 7/7

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Exhibit 99.18

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original document was prepared in Portuguese, and in case of any divergence, discrepancy or difference between this version and the Portuguese version, the Portuguese version shall prevail. The Portuguese version is the only valid and complete version and shall prevail for any and all purposes. There is no assurance as to the accuracy, reliability or completeness of the translation. Any person reading this translation and relying on it should do so at his or her own risk.

CALL OPTION AGREEMENT, AND OTHER COVENANTS

AMONG

PORTUGAL TELECOM INTERNATIONAL FINANCE B.V.

PT PORTUGAL SGPS, S.A.

AND

PORTUGAL TELECOM, SGPS S.A.

AND, FURTHER,

TELEMAR PARTICIPAÇÕES S.A.

AND

OI S.A.

DATED SEPTEMBER 8, 2014.

SHARE CALL OPTION AGREEMENT,

AND OTHER COVENANTS

By this instrument, the parties:

on the one side,

1. PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., a company incorporated under and governed by the laws of the Netherlands, headquartered in Amsterdam, the Netherlands, and with principal offices in Naritaweg 165, 1043 BW Amsterdam, the Netherlands, registered with the Amsterdam Chamber of Commerce under n.º 34108060, duly represented for the purposes hereof pursuant to its Bylaws (“PT Finance”);

2. PT PORTUGAL SGPS, S.A., a Portuguese corporation (sociedade anónima), headquartered at Avenida Fontes Pereira de Melo, n.º 40, in the district of São Jorge de Arroios, Lisbon, registered as a legal entity under n.º 507690737, with a capital stock of EUR 3,450,000,000.00 (three billion four hundred and fifty million Euros), duly represented for the purposes hereof pursuant to its Bylaws (“PT Holding” and together with PT Finance, the “Oi Controlled Entities”);

and on the other,

3. PORTUGAL TELECOM, SGPS S.A., a publicly held corporation governed by Portuguese law (sociedade aberta de direito português), headquartered at Avenida Fontes Pereira de Melo, n.º 40, in the district of São Jorge de Arroios, Lisbon, registered as a legal entity under n.º 503215058, with a capital stock of EUR 26,895,375 (twenty-six million, eight hundred ninety-five thousand, three hundred seventy-five Euros), duly represented for the purposes hereof pursuant to its Bylaws (“PT SGPS”);

and, further,

4. OI S.A., a Brazilian corporation (sociedade por ações) headquartered in the City and State of Rio de Janeiro, at Rua do Lavradio nº. 71, 2^nd floor, Center, registered with the CNPJ/MF under n°. 76.535.764/0001-43, duly represented for the purposes hereof pursuant to its Bylaws (“Oi”); and

5. TELEMAR PARTICIPAÇÕES S.A., a publicly held company (companhia aberta) headquartered at Praia de Botafogo nº. 300, 11^th floor, room 1101 (part), Botafogo, City of Rio de Janeiro, RJ, registered with the CNPJ/MF under n.º 02.107.946/0001-87, duly represented for the purposes hereof pursuant to its Bylaws (“Telemar Participações” or “CorpCo”);

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the parties described above shall also be referred to herein, individually, a “Party,” or together, the “Parties;” and

WHEREAS:

(i) On July 15, 2014, Oi and PT SGPS executed a Memorandum of Understanding (the “MOU”) establishing the conditions to fully implement the ongoing transaction involving the combination of the activities and businesses of PT SGPS and Oi;

(ii) Pursuant to the MOU, the Oi Controlled Entities will grant to PT SGPS an irrevocable, irreversible, personal and non-transferrable, in any way, call option to purchase shares issued by Oi (or by CorpCo, after the implementation of the merger of Oi shares into CorpCo in the context of the Transaction), under the terms and conditions established in this instrument,

the Parties RESOLVE to execute this Call Option Agreement, and Other Covenants (the “Agreement”), which will be governed by the provisions described below:

CLAUSE 1

SHARE CALL OPTION

1.1. Call Option. Subject to the condition subsequent established in Clause 2, the Oi Controlled Entities (the “Grantors of the Option”) hereby grant at the date hereof to PT SGPS an irrevocable, irreversible, personal and non-transferrable, in any way, call optionto acquire the Option Shares, as defined in Clause 1.1.1 below (the “Call Option”).

1.1.1. For the purposes of this Agreement, the “Option Shares” shall correspond, in aggregate, to 1,423,046,160 (one billion, four hundred twenty-three million, forty-six thousand, one hundred and sixty) shares issued by Oi, including 474,348,720 (four hundred seventy-four million, three hundred forty-eight thousand, seven hundred and twenty) common shares (“AON”) and 948,697,440 (nine hundred and forty-eight million, six hundred ninety-seven thousand, four hundred and forty) preferred shares issued by Oi (“APN”), held by each of the Oi Controlled Entities in the proportions indicated in Annex 1.1.1, provided, that once Oi shall have merged into CorpCo in the context of the Transaction (the “Merger of Shares”), the term “Option Shares” shall refer to 1,348,193,932 (one billion, three hundred forty-eight million, one hundred ninety-three thousand, nine hundred and thirty-two) common shares issued by CorpCo. Oi (and, after the Merger of Shares, CorpCo) may, subject to legal and regulatory restrictions, freely use the shares held in treasury. The number of Option Shares and the Exercise Price, as defined below, shall be adjusted to reflect any changes arising from share splits and reverse splits of shares issued by Oi or CorpCo, as applicable, as well as to reflect any distributions paid in shares, if such distributions result in a dilution of the Option Shares in

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relation to the shareholder base of Oi or CorpCo. For the avoidance of doubt, the number of Option Shares and the Exercise Price shall not be adjusted to reflect dividends paid in shares which, pursuant to their characteristics, provide a return to Oi or CorpCo shareholders, through the issuance of redeemable shares, if such shares are simultaneously redeemed for the amount corresponding to such return.

1.2. Period and Procedure for Exercising the Call Option. Subject to Clauses 1.2.1 through 1.2.5 below, PT SGPS may exercise the Call Option in whole or in part, in a single act or in distinct acts, at any time between the date hereof and the 6^th (sixth) anniversary of the Call Option Effective Date, as defined in Clause 2.1., by means of written communication delivered to any of the Oi Controlled Entities in accordance with Clause 5 below (“Exercise Notice”), which shall contain an express representation from PT SGPS that none of the events set forth in paragraphs (i) through (iii) of Clause 1.10 have occurred or shall have occurred at the Option Shares Transfer Date. The date of delivery of any Exercise Notice shall hereinafter be referred to as an “Exercise Date.”

1.2.1. The number of Option Shares shall be reduced annually in accordance with the schedule and percentages presented in the table below (“Exclusion”), if such Option Shares subject to Exclusion have not already been acquired by reason of the exercise of the Call Option:

1.3. Date, Time and Place for the Transfer of the Option Shares. PT Finance and/or PT Holding shall transfer, together or individually, to PT SGPS, the number of Option Shares indicated in the Exercise Notice at the corporate headquarters of Oi (or CorpCo, as applicable), at 1:00 p.m. on the 3^rd (third) Business Day following the Exercise Date (“Option Shares Transfer Date”).

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1.3.1. For the purposes of this Agreement, the term “Business Day” means any day other than a Saturday, Sunday, national holiday or other day on which the commercial banks are required to or may close, without undertaking banking activities and transactions in the City of São Paulo, State of São Paulo or the City of Rio de Janeiro, State of Rio de Janeiro.

1.4. Exercise Price of the Call Option. The price of exercise of the Call Option shall be R$1.8529 per APN and R$2.0104 per AON (the “Exercise Price”), to be paid in cash in immediately available funds, on the Option Shares Transfer Date, as consideration for the transfer of the respective Option Shares specified in the Exercise Notice. After the Merger of Shares, the Exercise Price shall be R$2.0104 per common share issued by CorpCo.

1.4.1. The Exercise Price shall be indexed to the variation of the CDI rate plus 1.5% (one and a half percent) per annum, calculated pro rata temporis, as from the Call Option Effective Date through the date of the effective payment of the Exercise Price for each exercise, whether partial or total, of the Call Option.

1.4.2. For the purposes of this Agreement, “CDI” refers to the average daily rate on overnight interbank deposits, represented by Certificados de Depósito Interbancário, as calculated by the CETIP S.A. – Mercados Organizados.

1.5. Settlement in Cash. If, in the event of exercise of the Call Option by PT SGPS, any of the Grantors of the Option and/or any of the Oi subsidiaries do not hold, in treasury, a sufficient number of Option Shares, free and clear of Encumbrances, to deliver to PT SGPS the Option Shares indicated in the Exercise Notice, PT Finance and/or PT Holding shall be obligated, together or individually, to settle their obligation by payment to PT SGPS, within the same period, of an amount in Brazilian currency corresponding to the difference between (i) the sale price of the Option Shares that should have been delivered to PT SGPS, in accordance with the trading price at the closing of the BM&FBovespa trading session on the Business Day immediately preceding the Exercise Date; and (ii) the respective Exercise Price corresponding to these shares (“Performance of the Option in Cash”).

1.5.1. Payment by any of the Grantors of the Option to PT SGPS of the amount relating to the Settlement of the Option in Cash (“Payment of the Option in Cash”) shall occur on the Option Shares Transfer Date set forth in Clause 1.3 above.

1.6. Default. Any failure by any of the Grantors of the Option to fulfill its obligations as set forth in this Clause shall require such defaulting Grantor, in addition to fulfillment of the obligation in default, to payment of a penalty for default corresponding to 2% (two percent) of the higher of (i) the market price of the Option Shares at the trading session on

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the last Business Day immediately preceding the Exercise Date; and (ii) the respective Exercise Price corresponding to such shares, plus interest on arrears corresponding to 12% (twelve percent) per annum, calculated pro rata temporis, and inflation indexing on the total of the amount accrued and unpaid, of the penalty and of the interest, calculated as of the date on which the obligation should have been fulfilled through the date of effective fulfillment.

1.7. Rights of the Option Shares. The Option Shares shall have the same characteristics and terms and shall enjoy the same statutory rights and privileges attributed respectively to the AONs and APNs of Oi at the Call Option Effective Date, or, if the Exercise of the Call Option occurs after the Merger of Shares of Oi, to the shares of CorpCo.

1.8. Integration of the Shareholder Bases. In the event of exercise of the Call Option, PT SGPS shall employ its best efforts to fulfill the objective of integrating the shareholder bases of PT SGPS and CorpCo, in the shortest possible period.

1.9. Limitation on the Purchase of Shares of Oi/CorpCo. For so long as the Call Option is in effect, PT SGPS may only buy shares issued by Oi or CorpCo through its exercise pursuant to the terms of this Agreement, and the purchase of shares issued by Oi or CorpCo by PT SGPS, directly or indirectly, by any other means is expressly prohibited.

1.10. Early Termination of the Call Option. Oi may declare the Call Option terminated, in its sole and exclusive discretion, upon written notice sent to PT SGPS in accordance in accordance with Clause 5 below, and PT SGPS shall not be entitled to acquire any of the remaining Option Shares, in the following events:

1.11. Joint and Several Obligations. Oi and CorpCo, the latter after the Merger of Shares, shall be jointly and severally liable with the Oi Controlled Entities for compliance with all their obligations as set forth in this Agreement.

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CLAUSE 2

CONDITION PRECEDENT

2.1. Condition Precedent. The Parties acknowledge that this Agreement is entered into subject to a condition precedent, under the terms of Article 125 et seq. of the Civil Code, and shall only come into effect on the date on which the exchange of common and preferred shares issued by Oi for securities issued by Rio Forte Investments, S.A becomes effective (the “Exchange”), as contracted by the Parties, on the date hereof, through the “Exchange Agreement, and Other Covenants.” The date on which the Exchange becomes effective is referred to in this Agreement as the “Call Option Effective Date.”

CLAUSE 3

REPRESENTATIONS AND WARRANTIES

3.1. PT SGPS’ Representations and Warranties. PT SGPS hereby represents and warrants to Oi, PT Finance, PT Holding and CorpCo that it has obtained all the necessary authorizations to execute this Agreement.

3.2. Oi’s Representations and Warranties. Oi, PT Finance, PT Holding and CorpCo hereby represent and warrant to PT SGPS that they have obtained all the necessary approvals to execute this Agreement.

CLAUSE 4

TERMINATION

4.1. This Agreement shall automatically terminate if the condition precedent set forth in Clause 2 is not satisfied by March 31, 2015.

4.2. Without prejudice to the exercise of all legal measures to which they are entitled, if fulfillment of any obligation fails to occur due to an act or omission by one of the Parties, the innocent Party may at its discretion claim specific performance of the obligation left unfulfilled by the other Party.

4.3. If a judicial, arbitral or administrative order that hinders the performance of this Agreement is handed down, the Parties undertake to, in good faith, and at their respective expenses, take all measures to protect the Agreement and its performance in accordance with its terms, toward eliminating, in the shortest possible period, all the effects of such order.

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4.3.1. Once the effects of the judicial, arbitral or administrative order have been eliminated, the Parties shall fulfill in full their obligations as set forth in this Agreement, without suspension or alteration, in faithful observance of the periods set forth contractually.

4.4. The provisions regarding conflict resolution set forth in Clause 6 shall survive termination of this Agreement.

CLAUSE 5

MISCELLANEOUS

5.1. Any communication, notice or subpoena relating to this Agreement, including notice of arbitration, shall be deemed delivered when received by the other Party (i) by registered mail, through a reputable courier company, at the time of effective receipt at the address(es) indicated below, (ii) at the time delivered, if delivered by hand, or (iii) on the date of confirmation of receipt of transmission issued by a fax machine, when faxed, as applicable, to the addresses and telephone/fax numbers shown below (or any other address or telephone/fax number as may be indicated by a Party, in writing, to the other Parties):

To Oi and the Oi Controlled Entities:

Attention: Bayard De Paoli Gontijo

Address: Rua Humberto de Campos, n.º 425, 8º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-2972

Fax: +55 21 3131-1155

Flavio Nicolay Guimarães

Address: Rua Humberto de Campos, n.º 425, 7º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-2227

Fax: +55 21 3131-1383

With copy to:

Eurico de Jesus Teles Neto

Address: Rua Humberto de Campos, n.º 425, 8º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-1207

Fax: +55 21 3131-1155

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To PT SGPS:

Attention: Secretaria Geral

Avenida Fontes Pereira de Melo nº. 40, freguesia de São Jorge de Arroios,

Concelho de Lisboa, Portugal

To Telemar Participações:

Attention: Sr. Fernando Magalhães Portella

Praia de Botafogo nº. 300, sala 1101, Botafogo, Rio de Janeiro, RJ, Brasil

5.1.1. Any Party may change the address to which notice shall be sent by written notice to the other contracting Parties in accordance with this Clause 5.1, it being however specified that for the purposes of this provision, the notice shall be deemed to have been received only upon acknowledgement of receipt by each of the other Parties.

5.2 This Agreement and its annexes contain the entire agreement and understanding in respect of the object of this instrument among the contracting Parties, and specifically replace any prior understanding of the Parties regarding the subject of this agreement.

5.3 The annexes to this Agreement constitute an integral and inseparable part of this Agreement, and the provisions thereof have the same force as the Clauses of this Agreement.

5.4 This Agreement may only be amended, replaced, cancelled, renewed or extended and its terms may only be waived through a written instrument signed by all Parties or, in the case of a waiver, by the Party waiving the respective right. No waiver, termination or discharge of this Agreement, or of any of its terms or provisions, shall be binding upon any of the contracting Parties unless confirmed in writing. Any delay in exercising a right, power or privilege provided for in this Agreement shall not be deemed a waiver of such right, power or recourse; nor shall the total or partial waiver of any right, power, recourse or privilege preclude any other subsequent exercise of such right, recourse, power or privilege.

5.5 This Agreement shall be binding upon and benefit the Parties and their respective permitted successors. This Agreement may not be assigned by any Party without the prior written consent of the other Parties.

5.5.1. Without the prior and express consent of Oi, PT SGPS may not assign or in any way transfer, in whole or in part, directly or indirectly, the Call Option, and may not create or grant any rights arising from the Call Option or, further, grant guarantees based on the Call Option.

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5.5.2. Notwithstanding the above, PT SGPS is hereby authorized to transfer the Call Option, one time, to any company in which PT SGPS holds a stake representing at least 99% of the voting and total share capital (a “PT SGPS Subsidiary”), provided, that (i) PT SGPS communicates the intention to transfer by written notice sent to Oi at least 5 days in advance, in accordance with Clause 5.1; and (ii) the PT SGPS Subsidiary adheres in full and without any qualifications to the terms and conditions of this Agreement and the Call Option. In this circumstance, PT SGPS and the assignee shall remain jointly and severally liable for the obligations PT SGPS assumes in this Agreement. Any subsequent transfer to another PT SGPS Subsidiary, even if it meets the requirements set forth in this Clause 5.5.2, shall require the prior and express consent of Oi, which shall not be unreasonably withheld.

5.5.3. PT SGPS may only grant or issue, directly or indirectly, derivatives backed by or referenced to shares issued by Oi or CorpCo if (i) it provides prior written notice to Oi detailing all the terms and conditions of the derivatives, in accordance with Clause 5.1; and (ii) it immediately utilizes all of the financial proceeds arising, directly or indirectly, from such transactions to acquire Option Shares, under the exact terms agreed to herein.

5.6 If any term or provision of this Agreement is declared void, invalid or ineffective, the Parties shall negotiate in good faith to replace the invalidated provisions with others that reflect, to the extent possible, their initial intentions.

5.7 The Parties shall bear their respective direct and indirect expenses incurred in connection with the negotiation and preparation of this Agreement and the consummation of the matters set forth herein.

5.7.1 Notwithstanding the other provisions in this Agreement, all taxes incident to the transactions contemplated by this Agreement and any capital gain (collectively, the “Taxes”), shall be the responsibility of the Party to which the obligation is imposed by law, and such Party shall present any and all the returns and other documents relating to the Taxes for which it is responsible.

5.8 The Parties acknowledge and agree that all the terms and conditions established in this Agreement shall be subject to specific performance, as provided for in the Brazilian Code of Civil Procedure.

5.9 The Parties further acknowledge that this Agreement constitutes an extrajudicial enforcement instrument (título executivo extrajudicial), under the terms of article 585, II, of the Brazilian Code of Civil Procedure.

5.10 This Agreement as signed is irrevocable and irreversible, and constitutes legal, valid and binding obligations, which shall be binding upon and benefit, the contracting Parties and their respective successors.

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5.11 The Parties undertake to respect the confidentiality of the information contained in this Agreement and in its annexes that qualifies as confidential information, and shall disclose the terms pertaining to the transactions that are the object of this Agreement and its annexes strictly to the extent necessary to fulfill legal or regulatory requirements to which the Parties are subject. The terms of any notice of a material fact, notice to the market or press release to be disclosed by the Parties and/or their controlled companies regarding the execution of this Agreement shall be submitted to the others in advance by each Party.

5.12 This Agreement shall be governed by and interpreted in accordance with the laws of the Federative Republic of Brazil.

CLAUSE 6

CONFLICT RESOLUTION

6.1 The Parties shall make an effort to resolve amicably and by consensus any controversy of any nature related directly or indirectly to this Agreement involving any of the Parties (“Conflict”).

6.2 If, after discussing for a period of 10 (ten) Business Days, the Parties fail to reach an amicable solution and consensus in relation to the Conflict, then such Conflict shall be settled by arbitration, to be conducted before and administered by the Câmara de Arbitragem da Câmara de Comércio Brasil-Canadá (the “Chamber”).

6.3 The arbitration shall be conducted in accordance with the Chamber’s procedural standards in effect at the time of the arbitration.

6.4 The arbitration shall be administered by an arbitral tribunal consisting of three arbitrators, it being specified that the chair of the tribunal shall be registered with the Ordem dos Advogados do Brasil (the “Arbitral Tribunal”).

6.4.1 Each Party Involved will appoint one arbitrator. If there is more than one claimant, the claimants shall appoint a single arbitrator by mutual agreement; similarly, if there is more than one respondent, the respondents shall appoint a single arbitrator by mutual agreement. The third arbitrator, who will preside over the Arbitral Tribunal, will be selected by mutual agreement of the arbitrators appointed by the Parties Involved.

6.4.2 Any omission, refusal, dispute, doubt and disagreement with respect to the appointment of the arbitrators by the Parties Involved or to the choice of the third arbitrator shall be settled by the Chamber.

6.4.3 The procedures provided for in this Clause shall also apply when replacing an arbitrator.

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6.5 The arbitration shall take place in the City of Rio de Janeiro, in the State of Rio de Janeiro, and the Arbitral Tribunal may, with cause, decide to carry out certain specific actions in different locations.

6.5.1 The arbitration shall be conducted in Portuguese.

6.5.2 The arbitration shall follow the rules of law (de direito), applying the rules and principles of the legal system of the Federative Republic of Brazil.

6.5.3 The arbitration shall have a term of 6 (six) months, which period may be extended for cause by the Arbitral Tribunal.

6.5.4 The arbitration will be confidential.

6.6 The Arbitral Tribunal shall allocate between the Parties, in accordance with criteria of succumbency (sucumbência), reasonability and proportionality, the payment and reimbursement of (i) any fees and other amounts due, paid or reimbursed to the Chamber, (ii) any fees and other amounts due, paid or reimbursed to the arbitrators, (iii) any fees and other amounts due, paid or reimbursed to the experts, translators, interpreters, stenographers and any other assistants as may have been appointed by the Arbitral Tribunal, (iv) any fees and expenses of the lawyers hired by the parties, to be reasonably established by the Arbitral Tribunal based on the receipts presented by the parties; (v) any reasonable travel expenses and fees of assistants or technical witnesses; and (vi) any damages for litigation in bad faith. The Arbitral Tribunal shall not condemn any of the Parties Involved to pay or reimburse contractual fees based on the success of the demand (ad exitum).

6.7 Arbitral awards shall be final and binding, neither requiring judicial ratification nor admitting any appeal, except for requests for correction (pedidos de correção) and requests for clarification to the Arbitral Tribunal as provided for under art. 30 of Law nº 9.307/96 and any annulment action based on art. 32 of Law nº 9.307/96.

6.8 Before the Arbitral Tribunal is seated, any of the Parties Involved may petition the Courts for preliminary injunctions and advance relief, although any such petition shall not affect the existence, validity and efficacy of this arbitration clause, nor represent a waiver of the obligation to submit the Conflict to arbitration. After the Arbitral Tribunal is seated, any petitions for preliminary injunctions or advance relief shall be directed to the Arbitral Tribunal.

6.9 For the purposes of (i) preliminary injunctions and advance relief before the Arbitral Tribunal is seated, (ii) enforcement of the decisions of the Arbitral Tribunal,

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including the final award and any partial award, (iii) any annulment action based on art. 32 of Law nº 9.307/96, and (iv) any Conflicts which, under Brazilian law cannot be settled through arbitration, the Forum of the Judicial District of Central Rio de Janeiro is elected as the sole jurisdiction, waiving all others, however special or privileged they may be.

IN WITNESS WHEREOF, the Parties cause 5 (five) originals of this Agreement, of equal substance and form, to be signed before 2 (two) witnesses.

Rio de Janeiro, September 8, 2014.

(Signature pages to follow)

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CALL OPTION AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 1/7

PORTUGAL TELECOM INTERNATIONAL FINANCE B.V.

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CALL OPTION AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 2/7

PORTUGAL TELECOM INTERNATIONAL FINANCE B.V.

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CALL OPTION AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 3/7

PORTUGAL SGPS, S.A.

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CALL OPTION AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 4/7

PORTUGAL TELECOM SGPS S.A.

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CALL OPTION AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 5/7

OI S.A.

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CALL OPTION AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 6/7

TELEMAR PARTICIPAÇÕES S.A.

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CALL OPTION AGREEMENT, AND OTHER COVENANTS ENTERED INTO AMONG PORTUGAL TELECOM INTERNATIONAL FINANCE B.V., PT PORTUGAL SGPS, S.A., PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 7/7

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Annex 1.1.1

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Exhibit 99.19

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original document was prepared in Portuguese, and in case of any divergence, discrepancy or difference between this version and the Portuguese version, the Portuguese version shall prevail. The Portuguese version is the only valid and complete version and shall prevail for any and all purposes. There is no assurance as to the accuracy, reliability or completeness of the translation. Any person reading this translation and relying on it should do so at his or her own risk.

TERMS OF COMMITMENT

AMONG

PORTUGAL TELECOM, SGPS S.A.

OI S.A.

AND

TELEMAR PARTICIPAÇÕES S.A.

DATED SEPTEMBER 8, 2014

TERMS OF COMMITMENT

By way of this instrument, the parties:

of the First Part,

1. PORTUGAL TELECOM, SGPS S.A., a publicly held corporation governed by Portuguese law (sociedade aberta de direito português), headquartered at Avenida Fontes Pereira de Melo, n.º 40, in the district of São Jorge de Arroios, Lisbon, registered as a legal entity under n.º 503215058, with a capital stock of EUR 26,895,375 (twenty-six million, eight hundred ninety-five thousand, three hundred seventy-five Euros), duly represented for the purposes hereof pursuant to its Bylaws (¨Portugal Telecom SGPS”);

and of the Second Part,

2. OI S.A., a Brazilian corporation (sociedade por ações) headquartered in the City and State of Rio de Janeiro, at Rua do Lavradio nº. 71, 2^nd floor, Center, registered with the CNPJ/MF under n°. 76.535.764/0001-43, duly represented for the purposes hereof pursuant to its Bylaws (“Oi”); and

3. TELEMAR PARTICIPAÇÕES S.A., a publicly held company (companhia aberta) headquartered at Praia de Botafogo nº. 300, 11^th floor, room 1101 (part), Botafogo, City of Rio de Janeiro, RJ, registered with the CNPJ/MF under n.º 02.107.946/0001-87, duly represented for the purposes hereof pursuant to its Bylaws (“Telemar Participações” or CorpCo”);

The parties identified above hereinafter shall be called, individually, “Party”, and jointly, “Parties”.

WHEREAS:

(i) On July 15, 2014, Oi and Portugal Telecom SGPS executed a Memorandum of Understanding (“MOU”) establishing the principles, terms, and conditions for the adjustments needed to fully implement the ongoing transaction involving the combination of the activities and businesses of Portugal Telecom SGPS and Oi (“Transaction”);

(ii) On July 28, 2014, Oi and Portugal Telecom SGPS agreed to the terms and conditions of the agreements to be executed between Oi and PT within the scope of the Transaction, which terms shall be submitted to the shareholders of Portugal Telecom SGPS, on the basis of a proposal of the Board of Directors of PT, and also to the Board of Directors of Oi;

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(iii) The parties further agreed to modify certain stages of the Transaction as set forth in the Memorandum of Understanding executed on October 1, 2013, and the Definitive Agreements relating to the Transaction executed on February 19, 2014, in particular to account for the fact that the merger of Portugal Telecom SGPS into CorpCo will no longer be implemented within the scope of the Transaction; and

(iv) Notwithstanding the necessary adjustments to the structure of the Transaction to allow for its full implementation, the Parties wish to leave unaltered certain concepts and principles initially agreed upon which justify the Transaction, including, but not limited to, the undertaking of each party to carry out its best efforts to fulfill the objective of integrating the shareholder bases of Oi and Portugal Telecom SGPS in CorpCo pursuant to a legally permissible structure (“Integration of the Shareholder Bases”), as well as listing the shares of CorpCo on the Novo Mercado segment of the BM&FBOVESPA, SA – Bolsa de Valores, Mercadorias e Futuros, on the regulated market of Euronext Lisbon, and on the New York Stock Exchange,

THE PARTIES RESOLVE to enter into these Terms of Commitment (“Agreement”), which shall be governed according to the following provisions:

CLAUSE 1

INTEGRATION OF SHAREHOLDER BASES AND LISTING

1.1 For the purposes of the Integration of the Shareholder Bases, as described in Recital (iii) above, the Parties hereby undertake to use their respective best efforts and to take all reasonable measures to implement the listing of CorpCo shares on the Novo Mercado segment of the BM&FBOVESPA, SA – Bolsa de Valores, Mercadorias e Futuros, as well as the listing of CorpCo shares (or securities backed by CorpCo shares) on the regulated market of Euronext Lisbon (“Listing”) and on the New York Stock Exchange, concurrently with the approval of the merger of Oi shares by CorpCo by the general shareholder meetings of said companies (“Merger of Shares”), it being however specified that, in the event that the Listing together with the approval of the Merger of Shares is not possible for any reason beyond the control of the Parties, the Parties agree to use their best efforts and to take all reasonable measures to implement the Listing as soon as possible following the Merger of Shares.

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1.2 The Parties further undertake to perform all acts, provide any required information, prepare all necessary documentation and to present and duly file all necessary filings before all appropriate governmental bodies and authorities, so as to implement the Listing and the Integration of the Shareholder Bases as soon as possible after the date hereof.

1.2.1 Without limiting the provisions of Clause 1.2, the Parties undertake to perform all necessary acts to implement the Integration of the Shareholder Bases relating to all Oi shares (or, following completion of the Merger of Shares, Corpco shares) held by Portugal Telecom SGPS as of the date hereof or that said company shall come to hold for so long as this Agreement is in force, including, but not limited to, (i) preparing and filing any prospectuses, including for admission to trading, registration statements (including on Form F-4 or Form F-3, where applicable) or other documents with the Brazilian Securities Commission (Comissão de Valores Mobiliários, or “CVM”), the Portuguese Securities Commission (Comissão do Mercado de Valores Mobiliários, or “CMVM”), Euronext Lisbon – Sociedade Gestora de Mercados Regulamentados (“Euronext Lisbon”) and the U.S. Securities and Exchange Commission (“SEC”) by Portugal Telecom SGPS, Oi, and/or CorpCo, as the case may be, including the preparation of audited and unaudited financial statements required by the rules of such government authorities, and (ii) hiring independent auditors, independent financial institutions or other experts to prepare financial statements, valuation reports and/or other necessary reports or documents and to use best efforts to cause such experts to consent to the inclusion their reports or other documents in the abovementioned prospectuses, registration statements or other documents to be filed with CVM, CMVM, Euronext Lisbon and the SEC. The Parties agree that the Integration of the Shareholder Bases may be implemented through different structures throughout the term of this Agreement, to the extent they are legally permissible, but agree that nothing in this Clause 1.2.1 or elsewhere in this Agreement shall require the Parties to implement any merger or incorporation of Portugal Telecom SGPS into CorpCo.

1.3 Oi undertakes to attend any General Meetings of the Shareholders of Portugal Telecom SGPS convened for the purposes of resolving on the legal or corporate acts necessary for the Integration of the Shareholder Bases, whether through a reduction of the share capital of Portugal Telecom SGPS, pursuant to the alternative structure under analysis described in the Information Statement issued by Portugal Telecom SGPS, dated August 13, 2014, or through another legally permissible alternative structure, and to vote in favor of approval of the aforementioned corporate and legal acts, to the extent Oi’s legitimate interests are preserved.

1.4 The obligations assumed by the Parties by the terms of the above Clauses 1.2 and 1.3 shall apply equally in the event the Integration of the Shareholder Bases continues in respect of any Oi shares (or, following completion of the Merger of Shares, CorpCo shares) that Portugal Telecom SGPS may receive upon exercise of the call option granted under the Share Call Option Agreement, and Other Covenants entered into on the date hereof, among Portugal Telecom SGPS, PT International Finance B.V., PT Portugal SGPS S.A., Oi, and TelemarParticipações (“Call Option”).

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CLAUSE 2

INDEMNIFICATION

2.1 In the event any of the Parties should breach any of its undertakings or obligations established under this Agreement, such defaulting Party shall indemnify, defend, and hold harmless the other Parties against any damages suffered by them, resulting or arising from such breach.

2.2 The Parties agree that indemnification for losses and damages caused by the breach of any of the provisions contained herein, based on a final ruling of a competent court that such breach occurred, may not be sufficient to wholly indemnify the non-defaulting Party. For this reason, the Parties agree that they shall be entitled to demand specific performance of their respective obligations or preventive measures against the occurrence of any breach of this Agreement. The use of specific performance or any preventive measures shall not be considered the exclusive mechanism to remedy any breach of this Agreement by any of the Parties; on the contrary, it shall be considered a right in addition to any other mechanisms provided for herein or by law.

CLAUSE 3

MISCELLANEOUS

3.1 The Agreement shall become effective as of the date hereof and remain in full force and effect until the Integration of the Shareholder Bases has been fully completed, including in respect of any Oi or CorpCo shares, as the case may be, that may be acquired by PT SGPS during the term of the Call Option.

3.2 Any communication, notice or subpoena relating to this Agreement, including notice of arbitration, shall be deemed delivered when received by the other Party (i) by registered mail, through a reputable courier company, at the time of effective receipt at the address(es) indicated below, (ii) at the time delivered, if delivered by hand, or (iii) on the date of confirmation of receipt of transmission issued by a fax machine, when faxed, as applicable, to the addresses and telephone/fax numbers shown below (or any other address or telephone/fax number as may be indicated by a Party, in writing, to the other Parties):

To Oi:

Attention: Bayard De Paoli Gontijo

Address: Rua Humberto de Campos, n.º 425, 8º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-2972

Fax: +55 21 3131-1155

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Flavio Nicolay Guimarães

Address: Rua Humberto de Campos, n.º 425, 7º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-2227

Fax: +55 21 3131-1383

With copy to:

Eurico de Jesus Teles Neto

Address: Rua Humberto de Campos, n.º 425, 8º andar, Leblon, CEP 22430-190,

Rio de Janeiro, RJ, Brasil

Telephone: +55 21 3131-1207

Fax: +55 21 3131-1155

To Portugal Telecom SGPS:

Attention: Secretaria Geral

Avenida Fontes Pereira de Melo nº. 40, freguesia de São Jorge de Arroios,

Concelho de Lisboa, Portugal

To Telemar Participações:

Attention: Sr. Fernando Magalhães Portella

Praia de Botafogo nº. 300, sala 1101, Botafogo, Rio de Janeiro, RJ, Brasil

3.2.1 Any Party may change the address to which notice shall be sent by written notice to the other contracting Parties in accordance with this Clause 3.1, it being however specified that for the purposes of this provision, the notice shall be deemed to have been received only upon acknowledgement of receipt by each of the other Parties.

3.3 This Agreement contains the entire agreement and understanding in respect of the object of this instrument among the contracting Parties, and specifically replaces any prior understanding of the Parties regarding the object of this instrument.

3.4 This Agreement may only be amended, replaced, cancelled, renewed or extended and its terms may only be waived through a written instrument signed by all Parties or, in the case of a waiver, by the Party waiving the respective right. No waiver, termination or release of this Agreement, or of any of its terms or provisions, shall be binding upon any of the contracting Parties unless confirmed in writing. Any delay in exercising a right, power or privilege provided for in this Agreement shall not be deemed a waiver of such right, power or recourse; nor shall the total or partial waiver of any right, power, recourse or privilege preclude any other subsequent exercise of such right, recourse, power or privilege.

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3.5 This Agreement shall be binding upon and benefit the Parties and their respective permitted successors. This Agreement (and the rights and obligations provided for herein) may not be assigned by any Party without the prior written consent of the other Parties.

3.6 If any term or provision of this Agreement is declared void, invalid or ineffective, the Parties shall negotiate in good faith to replace the invalidated provisions with others that reflect, to the extent possible, their initial intentions.

3.7 The Parties shall bear their respective direct and indirect expenses incurred in connection with the negotiation and preparation of this Agreement and the consummation of the matters set forth herein.

3.8 The Parties acknowledge and agree that all the terms and conditions established in this Agreement shall be subject to specific performance, as provided for in the Brazilian Code of Civil Procedure.

3.9 The Parties further acknowledge that this Agreement constitutes an extrajudicial enforcement instrument (título executivo extrajudicial), under the terms of article 585, II, of the Brazilian Code of Civil Procedure.

3.10 This Agreement as signed is irrevocable and irreversible, and constitutes legal, valid and binding obligations, which shall be binding upon and benefit, the contracting Parties and their respective successors and permitted assigns.

3.11 The Parties undertake to respect the confidentiality of the information contained in this Agreement that qualifies as confidential information, and shall disclose the terms pertaining to the transactions that are the subject of this Agreement and its exhibits strictly to the extent necessary to fulfill legal or regulatory requirements to which the Parties are subject. The terms of any notice of a material fact, notice to the market or press release to be disclosed by the Parties and/or their controlled companies regarding the execution of this Agreement shall be submitted to the others in advance by each Party.

3.12 This Agreement shall be governed by and interpreted in accordance with the laws of the Federative Republic of Brazil.

CLAUSE 4

CONFLICT RESOLUTION

4.1 The Parties shall make an effort to resolve amicably and by consensus any controversy of any nature related directly or indirectly to this Agreement involving any of the Parties (“Conflict”).

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4.2 If, after discussing for a period of 10 (ten) Business Days, the Parties fail to reach an amicable solution and consensus in relation to the Conflict, then such Conflict shall be settled by arbitration, to be conducted before and administered by the Câmara de Arbitragem da Câmara de Comércio Brasil-Canadá (the “Chamber”).

4.3 The arbitration shall be conducted in accordance with the Chamber’s procedural standards in effect at the time of the arbitration.

4.4 The arbitration shall be administered by an arbitral tribunal consisting of three arbitrators, it being specified that the chair of the tribunal shall be registered with the Ordem dos Advogados do Brasil (the “Arbitral Tribunal”).

4.4.1 Each Party Involved will appoint one arbitrator. If there is more than one claimant, the claimants shall appoint a single arbitrator by mutual agreement; similarly, if there is more than one respondent, the respondents shall appoint a single arbitrator by mutual agreement. The third arbitrator, who will preside over the Arbitral Tribunal, will be selected by mutual agreement of the arbitrators appointed by the Parties Involved and/or as set forth in the regulations of the arbitral chamber.

4.4.2 Any omission, refusal, dispute, doubt and disagreement with respect to the appointment of the arbitrators by the Parties Involved or to the choice of the third arbitrator shall be settled by the Chamber.

4.4.3 The procedures provided for in this Clause shall also apply when replacing an arbitrator.

4.5 The arbitration shall take place in the City of Rio de Janeiro, in the State of Rio de Janeiro, and the Arbitral Tribunal may, with cause, decide to carry out certain specific actions in different locations.

4.5.1 The arbitration shall be conducted in Portuguese.

4.5.2 The arbitration shall follow the rules of law (de direito), applying the rules and principles of the legal system of the Federative Republic of Brazil.

4.5.3 The arbitration shall have a term of 6 (six) months, which period may be extended for cause by the Arbitral Tribunal.

4.5.4 The arbitration will be confidential.

4.6 The Arbitral Tribunal shall allocate between the Parties, in accordance with criteria of succumbency (sucumbência), reasonability and proportionality, the payment and reimbursement of (i) any fees and other amounts due, paid or reimbursed to the Chamber, (ii) any fees and other amounts due, paid or reimbursed to the arbitrators, (iii) any fees and

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other amounts due, paid or reimbursed to the experts, translators, interpreters, stenographers and any other assistants as may have been appointed by the Arbitral Tribunal, (iv) any fees in succumbency and expenses of the lawyers and experts hired by the parties, to be reasonably established by the Arbitral Tribunal based on the receipts presented by the parties; (v) any reasonable travel expenses and fees of assistants or technical witnesses; and (vi) any damages for litigation in bad faith. The Arbitral Tribunal shall not condemn any of the Parties Involved to pay or reimburse contractual fees based on the success of the demand (ad exitum).

4.7 Arbitral awards shall be final and binding, neither requiring judicial ratification nor admitting any appeal, except for requests for correction (pedidos de correção) and requests for clarification to the Arbitral Tribunal as provided for under art. 30 of Law nº 9.307/96 and any annulment action based on art. 32 of Law nº 9.307/96.

4.8 Before the Arbitral Tribunal is seated, any of the Parties Involved may petition the Courts for preliminary injunctions and advance relief, although any such petition shall not affect the existence, validity and efficacy of this arbitration clause, nor represent a waiver of the obligation to submit the Conflict to arbitration. After the Arbitral Tribunal is seated, any petitions for preliminary injunctions or advance relief shall be directed to the Arbitral Tribunal.

4.9 For the purposes of (i) preliminary injunctions and advance relief before the Arbitral Tribunal is seated, (ii) enforcement of the decisions of the Arbitral Tribunal, including the final award and any partial award, (iii) any annulment action based on art. 32 of Law nº 9.307/96, and (iv) any Conflicts which, under Brazilian law cannot be settled through arbitration, the Forum of the Judicial District of Central Rio de Janeiro is elected as the sole jurisdiction, waiving all others, however special or privileged they may be.

IN WITNESS WHEREOF, the Parties cause 3 (three) counterparts of this Agreement, of equal substance and form, to be signed before 2 (two) witnesses.

Rio de Janeiro, September 8, 2014.

(Signature pages to follow)

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TERMS OF COMMITMENT ENTERED INTO AMONG PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 1/4

PORTUGAL TELECOM SGPS S.A.

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TERMS OF COMMITMENT ENTERED INTO AMONG PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 2/4

OI S.A.

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TERMS OF COMMITMENT ENTERED INTO AMONG PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 3/4

TELEMAR PARTICIPAÇÕES S.A.

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TERMS OF COMMITMENT ENTERED INTO AMONG PORTUGAL TELECOM, SGPS, S.A., OI S.A. AND TELEMAR PARTICIPAÇÕES S.A., ON SEPTEMBER 8, 2014.

SIGNATURE PAGE 4/4

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