UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 2)*

Oi S.A.

(formerly known as Brasil Telecom S.A.)

(Name of Issuer)

Common Shares, no par value

(Title of Class of Securities)

670851 104**

(CUSIP Number)

Luiz Otávio Mourão, Executive Director

AG Telecom Participações S.A.

Praia de Botafogo 300, 4th floor, sala 401 (parte)

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

Tel: +55 21 2211-8000

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

October 1, 2013

(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. 2 to Schedule 13D (this “Amendment”) amends the Statement on Schedule 13D filed with the Securities and Exchange Commission on February 27, 2012 (the “Initial 13D”) by Andrade Gutierrez Telecomunicações LTDA (“AGT”), PASA Participações S.A. (“PASA”) and AG Telecom Participações S.A. (“AG Telecom”), as amended by Amendment No. 1 to Schedule 13D (“Amendment No. 1”, the Initial 13D as amended by Amendment No. 1 and as further amended by this Amendment, this “Statement”) filed with the Securities and Exchange Commission on May 2, 2012 by AGT, PASA and AG Telecom by furnishing the information set forth below. This Amendment is being filed by AG Telecom, PASA and Andrade Gutierrez S.A. (the successor by merger to AGT, “AGSA”, and together with AG Telecom and PASA, the “Reporting Persons”). 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 and Amendment No. 1.

The Reporting Persons are filing this Amendment to revise information previously reported in light of the proposed business combination of Oi S.A. (“Oi S.A.”), Portugal Telecom SGPS, S.A. (“Portugal Telecom”), Telemar Participações S.A. (“TmarPart”), AG Telecom, PASA, LF Tel. S.A. (“LF Tel”), EDSP75 Participações S.A. (“EDSP75”), and Bratel Brasil S.A. (“Bratel”) announced on October 2, 2013 (the “Business Combination”). On October 1, 2013, AG Telecom and PASA entered into a Memorandum of Understanding (the “MOU”) with Oi S.A., Portugal Telecom, LF Tel, EDSP75, Bratel, Avistar, SGPS, S.A. (“BES”) and Nivalis Holding B.V. (“Ongoing”) with respect to the Business Combination. Pursuant to the MOU, among other things, (1) Oi S.A. is expected to become a wholly owned subsidiary of either TmarPart or a new entity to be organized for purposes of the Business Combination (in either case, the “Holding Company”), and (2) Portugal Telecom is expected to merge with and into the Holding Company with the Holding Company as the surviving entity. See Items 4, 6 and 7 below.

ITEM 1. SECURITY AND ISSUER

This Amendment relates to the common shares, no par value (the “Common Shares”), of Oi S.A., a corporation (sociedade anônima) organized under the laws of the Federative Republic of Brazil (“Brazil”), which has its principal executive offices located at Rua do Lavradio, No. 71, 2nd floor – Centro, 20230-070 Rio de Janeiro, RJ, Brazil (the “Issuer”).

ITEM 2. IDENTITY AND BACKGROUND

Item 2 is hereby amended and restated in its entirety as follows:

This Amendment is being filed jointly on behalf of each of the Reporting Persons. The agreement among the Reporting Persons to file this Amendment jointly in accordance with Rule 13d-1(k) of the Securities Exchange Act of 1934 is attached as Exhibit 99.1.

AGSA is the successor by merger to AGT. AGSA is a holding corporation (sociedade anônima) organized under the laws of Brazil principally engaged in managing the businesses of the Andrade Gutierrez Group. The Andrade Gutierrez Group is focused on three core businesses: (1) engineering and construction work in Brazil and abroad; (2) public concessions in Brazil; and (3) telecommunications in Brazil. The principal office of AGT is located at Av. do Contorno nº 8.123, Cidade Jardim, Belo Horizonte, MG, CEP 30110-937, Brazil.

PASA is a corporation (sociedade anônima) organized under the laws of Brazil principally engaged, through its subsidiaries, in managing the telecommunications business of the Andrade Gutierrez Group. The principal office of PASA is located at Av. do Contorno nº 8.123, Cidade Jardim, Belo Horizonte, MG, CEP 30110-937, Brazil.

AG Telecom is a corporation (sociedade anônima) organized under the laws of Brazil principally engaged, through its subsidiaries, in managing the telecommunications business of the Andrade Gutierrez Group. The principal office of AG Telecom is located at Praia de Botafogo nº 300, sala 401 (parte), Botafogo, CEP 22250-040, Rio de Janeiro, RJ, Brazil.

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The name, present principal occupation or employment (and the name, principal business and address of any corporation or other organization in which such employment is conducted) and citizenship of each director and executive officer, as applicable, of each Reporting Person is provided in Exhibit 99.2, which is incorporated by reference herein.

During the last five years, none of the Reporting Persons nor, to the knowledge of the Reporting Persons, any of the persons listed in Exhibit 99.2 has (i) been convicted in any criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction such that, as a result of such proceeding, such person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activity subject to, federal or state securities laws or finding any violation with respect to such laws.

ITEM 4. PURPOSE OF TRANSACTION

The last paragraph of Item 4 of the Initial 13D is hereby amended and restated in its entirety as follows:

On October 1, 2013, AG Telecom and PASA entered into the MOU with Oi S.A., Portugal Telecom, LF Tel, EDSP75, Bratel, BES and Nivalis with respect to the Business Combination.

Oi S.A. Capital Increase

As part of the Business Combination, Oi S.A. proposes to undertake a capital increase (the “Oi Capital Increase”). The estimated amount of the Oi Capital Increase as of the date of the MOU is approximately R$14.1 billion, with the approximate amount to be paid in cash of a minimum of R$7.0 billion, with the objective of reaching R$8.0 billion, and the approximate amount to be paid with the PT Assets (as defined below) of R$6.1 billion. The Oi Capital Increase is expected to be conducted through the public issuance of common shares and preferred shares of Oi S.A., preferably in proportion to the current ratio between the issued and outstanding common and preferred shares of Oi S.A.; provided that in order to respect the legal limit for division of capital between voting and non-voting shares (i.e., minimum of one third of the shares entitled to vote and maximum of two thirds of shares without voting rights), the number of issued shares of each type may be adjusted. The Oi Capital Increase will be subject to the full subscription of the minimum value of the portion to be paid up in cash and will be subject to certain conditions, as described below.

The Reporting Persons understand that Portugal Telecom will enter into a commitment to subscribe and pay for the portion of the Oi Capital Increase to be paid for through the contribution of assets (the “PT Assets”) through the contribution of its share interests in companies that hold all of (1) the operating assets of Portugal Telecom, except the equity interests directly or indirectly held in Oi S.A. and Contax Participações S.A., and (2) the liabilities of Portugal Telecom on the date of such contribution. Pursuant to Law No. 6,404/76 (the “Brazilian Corporations Law”), the PT Assets will be identified and subject to valuation by a specialized company, whose valuation report will be submitted to the General Meeting of shareholders of Oi S.A.

Portugal Telecom estimates that the equity value of the PT Assets, upon assessment for the purposes of the contribution to Oi S.A., correspond to a value within a range of values with a minimum of €1.9 billion and maximum of €2.1 billion, equivalent to R$5.8 billion and R$6.4 billion, respectively, based on the current exchange rate of 3.0181 reais per euro. Portugal Telecom may elect not to consummate the subscription of shares in the Oi Capital Increase if the valuation report of the PT Assets values the PT Assets in euros at a value lower than the estimated values above, based on the exchange rate of euros to reais on the date of the valuation report.

Current shareholders of TmarPart, and BTG Pactual S.A., directly or through an investment vehicle managed and administered through Banco BTG Pactual S.A., will participate in the offering by placing a subscription order for approximately R$2.0 billion.

The holders of common shares and preferred shares of Oi S.A. will have priority in the subscription of the Oi Capital Increase. TmarPart, AG Telecom and LF Tel will assign all of their respective priority rights to Portugal Telecom free of charge.

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Once the subscription period for the Oi Capital Increase is closed, Portugal Telecom may elect not to consummate the Business Combination and all other corporate transactions related to the Business Combination if the percentage of the participation of Portugal Telecom in the Holding Company is equal to or less than 36.6% of the total capital of the Holding Company on a fully diluted basis after giving effect to the merger of shares of Oi S.A. and the Holding Company (as described below). Additionally, TmarPart may elect not to consummate the Business Combination and all other corporate transactions related to the Business Combination if the percentage of the participation of Portugal Telecom in the Holding Company is greater than 39.6% of the total capital of the Holding Company on a fully diluted basis after giving effect to the merger of shares of Oi S.A. and the Holding Company.

The other conditions of the Oi Capital Increase will be set forth in the definitive agreements that govern the Business Combination.

Recapitalization and Reorganization of AG Telecom and PASA

As part of the Business Combination, AG Telecom and TmarPart will be capitalized with the resources needed to repay their indebtedness. In addition, AG Telecom and PASA will be reorganized in order to separate the assets not related to their direct or indirect shareholding in Oi, so that AG Telecom and TmarPart will not have assets or liabilities (or will have cash or cash equivalents equal to their respective liabilities), other than: (1) shares of TmarPart and Oi, in the case of AG Telecom; and (2) shares of Oi, held directly or indirectly, in the case of TmarPart. Following this recapitalization, PASA will merge with and into AG Telecom, and subsequently AG Telecom will merge with and into TmarPart.

Merger of Shares between Oi S.A. and the Holding Company

The MOU provides that following the Oi Captial Increase, Oi S.A. and the Holding Company will convene shareholders meetings to consider a merger of shares (incorporação de ações), with a view to causing Oi S.A. to become a wholly-owned subsidiary of the Holding Company and to facilitate the migration of the shareholder base of Oi S.A. to the Holding Company (the “Merger of Shares”). At the effective time of the Merger of Shares, the Holding Company will have no assets or liabilities (or will have cash equivalent equal to its liabilities), other than the shares of Oi S.A. that it holds.

In the proposed Merger of Shares, holders of Oi S.A. common shares will receive one new common share issued by the Holding Company in exchange for each common share of Oi S.A. that they hold, and holders of Oi S.A. preferred shares will receive one new common share issued by the Holding Company in exchange for each 1.0857 preferred share of Oi S.A. that they hold. All ratios in the mergers that are part of the Business Combination were established based on market prices of the shares of Oi S.A. in a period of 30 days and considering the shares of Oi S.A. that the companies involved in the operation directly or indirectly hold, assuming that such companies will not hold any liabilities or assets (or will have cash or cash equivalents equal to their respective liabilities).

Merger of Portugal Telecom with and into the Holding Company

The MOU provides that Portugal Telecom will merge with and into the Holding Company (the “Portugal Telecom Merger”), pursuant to art. 227 of the Brazilian Corporations Law. As a result of the proposed Portugal Telecom Merger, Portugal Telecom’s assets will be transferred by operation of law to the Holding Company. The Portugal Telecom Merger will be submitted to the General Meeting of shareholders of the Holding Company for consideration in conjunction with the Merger of Shares. In addition, the Portugal Telecom Merger will be submitted for consideration to the General Meeting of shareholders of Portugal Telecom. At the time of the proposed Portugal Telecom Merger, Portugal Telecom will have no assets or liabilities (or will have cash and cash equivalents equal to its liabilities), other than shares of the Holding Company. In the proposed Portugal Telecom Merger, the shareholders of Portugal Telecom will receive a number of common shares issued by the Holding Company equal to the number of common shares of the Holding Company that will be held by Portugal Telecom immediately prior to such merger.

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Listing and Corporate Governance of the Holding Company

The MOU provides that the Holding Company will apply to be listed on the Novo Mercado segment of the BM&FBOVESPA S.A. – Bolsa de Valores, Mercadorias e Futuros (“BM&FBOVESPA), with the aim of strengthening its corporate governance through the adoption of a new management structure and corporate governance regime. The Holding Company will also apply to be listed on the New York Stock Exchange (“NYSE”) and the NYSE Euronext Lisbon.

The MOU provides that the Holding Company will have a Board of Directors consisting of eleven (11) members and eleven (11) alternate members. Members of the Board of Directors of the Holding Company to be elected in anticipation of the listing of the Holding Company on the Novo Mercado segment and the Merger of Shares will have a term of three (3) years from their election or until the General Meeting of the shareholders of the Holding Company to examine the financial statements of the Holding Company for the third fiscal year ending after the close of the year in which the Merger of Shares occurs, whichever occurs last. In order to facilitate the integration of Oi S.A. and Portugal Telecom, the Board of Directors of the Holding Company shall initially consist of the following members: Alexandre Jereissati Legey, Amilcar Morais Pires, Fernando Magalhães Portella, Fernando Marques dos Santos, Henrique Manuel Fusco Granadeiro, José Maria Ricciardi, José Mauro Mettrau Carneiro da Cunha, Nuno Rocha dos Santos de Almeida, Rafael Luís Mora Funes, Renato Torres de Faria and Sergio Franklin Quintella.

The MOU provides that Mr. José Mauro Carneiro da Cunha Mettrau and Henrique Manuel Fusco Granadeiro will assume the positions of President and Vice President, respectively, of the Board of Directors of the Holding Company. Mr. Zeinal Bava, current CEO of Oi and CEO of PT Portugal, will be the CEO of the Holding Company and its subsidiaries.

The MOU provides that immediately after the implementation of the corporate actions described above, the Shareholders’ Agreements of AG Telecom, LF Tel, TmarPart entered into or amended as of January 25, 2011 will be terminated.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER

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

As of October 7, 2013, based solely on information provided in the Annual Report on Form 20-F submitted to the SEC by the Issuer on April 30, 2013, the total number of issued and outstanding Common Shares is 514,757,934, excluding 84,250,695 Common Shares held in treasury, and TmarPart beneficially owns, and has the sole power to vote and dispose of, 290,549,788 Common Shares, representing 56.4% of the issued and outstanding Common Shares.

(a) & (b) AG Telecom:

As of October 7, 2013, AG Telecom owns 565,880,376 common shares of TmarPart, representing 19.4% of the issued and outstanding common shares of TmarPart. However, pursuant to the shareholders’ agreements described in Item 6 of this Statement, AG Telecom may be deemed to beneficially own all of the Common Shares beneficially owned by TmarPart. AG Telecom disclaims beneficial ownership of such Common Shares, other than with respect to its proportionate interest in these shares.

AG Telecom does not have a board of directors or other similar body. Other than as set forth in the table below, as of October 7, 2013, none of the executive officers of AG Telecom beneficially owns any Common Shares. AG Telecom disclaims beneficial ownership of such securities of the Issuer beneficially owned by such executive officers.

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PASA:

As of October 7, 2013, PASA does not directly own any Common Shares and owns all of the common shares of AG Telecom. As discussed above, AG Telecom may be deemed to beneficially own all of the Common Shares beneficially owned by TmarPart. PASA disclaims beneficial ownership of such Common Shares, other than with respect to its proportionate interest in these shares.

PASA does not have a board of directors or other similar body. Other than as set forth in the table below, as of October 7, 2013, none of the executive officers of PASA beneficially owns any Common Shares. PASA disclaims beneficial ownership of such securities of the Issuer beneficially owned by such executive officers.

AGSA:

As of October 7, 2013, AGSA does not directly own any Common Shares and owns 65.0% of the outstanding common shares of PASA, which owns all of the common shares of AG Telecom. As discussed above, AG Telecom may be deemed to beneficially own all of the Common Shares beneficially owned by TmarPart. AGSA disclaims beneficial ownership of such Common Shares, other than with respect to its proportionate interest in these shares.

Other than as set forth in the table below, as of October 7, 2013, none of the directors and executive officers of AGSA beneficially owns any Common Shares. AGSA disclaims beneficial ownership of such securities of the Issuer beneficially owned by such directors and executive officers.

In addition, pursuant to the shareholders’ agreements described in Item 6 of this Statement, the Reporting Persons may be deemed to be members of a group, with Jereissati Telecom S.A., EDSP75, LF Tel, Portugal Telecom and Bratel (collectively, the “Potential Group Members”), which shares the power to vote and the power to dispose of the Common Shares beneficially owned by TmarPart. Each of the Reporting Persons disclaims membership in any such group. Pursuant to the PASA Shareholders’ Agreement described in Item 6 of this Statement, AGSA may be deemed to be a member of a group, with Bratel, which shares the power to vote and the power to dispose of the Common Shares beneficially owned by AG Telecom. AGSA disclaims membership in any such group.

The following information with respect to the Potential Group Members is based solely on information provided by TmarPart.

Jereissati Telecom is a corporation (sociedade anônima) organized under the laws of Brazil principally engaged, through its subsidiaries, in managing the telecommunications business of the Jereissati Group. The Jereissati Group partially owns and manages 15 shopping malls in the Southern and Southeastern regions of Brazil. The principal office of Jereissati Telecom is located at Rua Angelina Maffei Vita, nº 200, 09th floor, CEP 01455-070, in the city of São Paulo, state of São Paulo, Brazil.

EDSP75 is a corporation (sociedade anônima) organized under the laws of Brazil principally engaged, through its subsidiaries, in managing the telecommunications business of the Jereissati Group. The principal office of EDSP75 is located at Rua Angelina Maffei Vita, nº 200, 09th floor, CEP 01455-070, in the city of São Paulo, state of São Paulo, Brazil.

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LF Tel is a corporation (sociedade anônima) organized under the laws of Brazil principally engaged, through its subsidiaries, in managing the telecommunications business of the Jereissati Group. The principal office of LF Tel is located at Rua Angelina Maffei Vita, nº 200, 09th floor, CEP 01455-070, in the city of São Paulo, state of São Paulo, Brazil.

Portugal Telecom is a limited liability holding company organized under the laws of the Portuguese Republic principally engaged, through its subsidiaries, in providing telecommunications services. The principal executive offices of Portugal Telecom are located at Avenida Fontes Pereira de Melo, 40, 1069-300 Lisboa, Portugal.

Bratel Brasil is a corporation organized under the laws of the Federative Republic of Brazil principally engaged, through its subsidiaries, in managing the investments of Portugal Telecom, directly and indirectly, in the Issuer. The principal executive offices of Bratel Brasil are located at Rua Cubatao, 320, 4th floor, São Paulo, Brazil.

To the knowledge of the Reporting Persons, based solely on information provided by TmarPart, during the last five years, none of the Potential Group Members has (i) been convicted in any criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction such that, as a result of such proceeding, such person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activity subject to, federal or state securities laws or finding any violation with respect to such laws.

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 of the Initial 13D is hereby amended by adding the following paragraphs at the end thereof:

On October 1, 2013, AG Telecom and PASA entered into the MOU with Oi S.A., Portugal Telecom, LF Tel, EDSP75, Bratel, BES and Nivalis with respect to the Business Combination.

As part of the Business Combination, the parties to the MOU have proposed that Oi S.A. enter into the Merger of Shares with the Holding Company as described under the caption “Merger of Shares between Oi S.A. and the Holding Company” in Item 4 of this Amendment No. 2. Under Section 8 of the MOU, AG Telecom and PASA have agreed, together with the other parties to the MOU, to develop negotiations with a view to achieving the objectives set forth in the MOU, and that such negotiations shall be guided according to the dictates of good faith. AG Telecom and PASA have agreed, together with the other parties to the MOU, to use their best efforts to, within the term of the MOU, or its possible extensions, obtain all necessary approvals by the governing bodies of Oi S.A. and Portugal Telecom, and negotiate and conclude the Prior Meeting of shareholders of TmarPart, which will address all the steps and conditions of the Business Combination, and the definitive agreements, contemplating the measures necessary for implementation of the Business Combination, as set forth in the terms of the MOU. The MOU provides that upon the completion of the Business Combination, all the shareholders’ agreements described in Section 6 of the Initial 13D will be terminated.

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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: October 8, 2013

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EXHIBIT 99.1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the following:

The Joint Filing Agreement may be executed in any number of counterparts all of which together shall constitute one and the same instrument.

IN WITNESS WHEREOF, the undersigned hereby execute this Agreement as of this 8^th day of October, 2013.

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 Andrade Gutierrez S.A.

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

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Executive Officers of PASA Participações S.A.

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

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Executive Officers of AG Telecom Participações S.A.

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

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Exhibit 99.9

This document is a free translation only. Due to the complexities of language translation, translations are not always precise. The original Memorandum of Understanding 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.

MEMORANDUM OF UNDERSTANDING

This Memorandum of Understanding (“MOU”) is entered into for the purpose of consolidating the alliance between Portugal Telecom, SGPS S.A. (“Portugal Telecom”) and Oi S.A. (“Oi”) that was established in 2010 and developed since that time through mutual investments held by Portugal Telecom and Oi, with the aim of developing a global telecommunications enterprise, which would allow, through this industrial alliance, cooperation in various areas, sharing of best practices, increased economies of scale, R&D initiatives, technology development and expansion of the international presence of Portugal Telecom and Oi, notably in Brazil, Portugal and Africa, diversification of services, maximization of synergies and reduction of costs, always seeking to offer better services and customers care for both groups and to create value for their shareholders (the “Industrial Alliance”).

Thus, under the Industrial Alliance, by this MOU, Oi, Portugal Telecom, AG Telecom Participações S.A. (“AG”), LF Tel S.A. (“LF”), PASA Participações S.A. (“PASA” ), EDSP75 Participações S.A. (“EDSP75”), Bratel Brasil S.A. (“Bratel Brasil”), Avistar, SGPS, S.A. (“BES”) and Nivalis Holding B.V. (“Ongoing”) set forth the principles, terms and conditions negotiated with the goal of completing a transaction (the “Transaction”) involving the combination of the business and affairs of Portugal Telecom and Oi, to be held by a single company, Telemar Participações S.A. (“TelPart”) or another company constituted for that purpose (in either case, “CorpCo”), which will have a widely held shareholder base comprised of the shareholders of Portugal Telecom, TelPart and Oi, with the capital of Corpco divided into a single series of common shares, which will be traded on BM&FBovespa S.A. – Bolsa de Valores, Mercadorias e Futuros (“BM&FBOVESPA”), the NYSE Euronext Lisbon and the New York Stock Exchange (“NYSE”), and will adhere to the rules of corporate governance of the Novo Mercado segment of BM&FBOVESPA (the “Formation of Corpco”). Each of Oi, Portugal Telecom, AG, LF, PASA, EDSP75, Bratel Brasil, BES and Ongoing is individually referred to as a “Party” and collectively as “Parties”.

The consummation of the Transaction, including a reorganization of the chain of control of Oi (the “TelPart Reorganization”), which, for purposes of this instrument, forms a part of the “Transaction,” is contingent upon the implementation of the various steps after obtaining the necessary consents, including corporate and regulatory authorizations, in all applicable jurisdictions, without prejudice to the adoption of other measures that may arise in the course of negotiations, during the period set forth herein, which are deemed necessary following the signing of this MOU. The parties agree to negotiate in good faith after the date of this MOU based on the terms and conditions contained herein for the consummation of the Transaction.

The Parties intend to establish the principles that will govern the negotiations of a series of transactions intended to consolidate the Industrial Alliance upon the consummation of the Transaction, with the primary objective of combining the business and activities developed by Oi and Portugal Telecom, namely in Brazil, Portugal and Africa.

The Industrial Alliance, including the strategic partnership and cooperation in various areas developed between Oi and Portugal Telecom since 2010, when Portugal Telecom became a shareholder of Oi and vice versa, permitted Oi and Portugal Telecom to identify potential synergies, efficiencies and opportunities whose full realization depends on the effective combination of business and activities of these companies through the Formation of Corpco.

Corpco, from its geographical base in Brazil, Portugal and Africa, with 260 million inhabitants, will occupy a considerable space in the global telecommunications industry, particularly in developing markets. Corpco will be able to meet the need to investment with a view to the improvement and expansion of services, will benefit from economies of scale, and will unify and develop its technological know-how, leveraging its expertise in the Portuguese-speaking markets and other markets, without limitation, with its resulting global positioning in a highly competitive industry.

Upon consummation of the Transaction, the business and affairs of Oi and Portugal Telecom will be, therefore, under the control and management of a single company, allowing the acceleration of the development of Oi in Brazil, the leveraging and further enhancement of the capacity for innovation of Portugal Telecom, and the realization of synergies.

For these reasons, the objective of integrating the operations of Portugal Telecom and Oi under the control of a single company will be guided by the following principles:

The following are the corporate actions and steps to be implemented for the consummation of the Transaction:

3.1.1 The Oi Capital Increase will be effected through the public subscription for common and preferred shares, preferably in proportion to the current ratio between issued and outstanding common and preferred shares of Oi. This ratio may be adjusted to comply with the legal limit

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between voting and non-voting shares. The shares issued shall be paid upon subscription in cash or assets, and the portion paid in assets will be fully paid by Portugal Telecom, through the contribution of the PT Assets (as defined in Item 4).

3.1.2 The estimated amount of the Oi Capital Increase as of the date of this MOU is approximately R$14.1 billion, with the approximate amount to be paid in cash of a minimum of R$7.0 billion, with the objective of reaching R$8.0 billion, and the approximate amount to be paid with the PT Assets of R$6.1 billion. The Definitive Agreements will provide that the Capital Increase of Oi will be subject to the full subscription of the minimum value of the portion to be paid in cash. For the purpose of this MOU, all of the percentages and amounts that follow presume the objective of using R$8.0 billion in cash to effect the Oi Capital Increase.

3.1.3 The portion of the Oi Capital Increase to be paid in cash will have a settlement guarantee provided by a consortium of banks (the “Underwriters”), in accordance with the terms and conditions to be negotiated with the Underwriters in a separate instrument, subject to market conditions at the time and the necessary approvals of the Underwriters. Additionally, current shareholders of TelPart, and BTG Pactual S.A., directly or through an investment vehicle managed and administered through Banco BTG Pactual S.A., will participate in the offering by placing a subscription order for approximately R$2.0 billion.

3.1.4 Portugal Telecom will execute a commitment to subscribe for the portion of the Oi Capital Increase to be paid for through the contribution of all the assets that are identified in the Valuation Report on PT Assets defined in Item 4 of this MOU, at the price per share of the Oi Capital Increase.

3.1.5 The shareholders of Oi will have priority in the subscription of the Oi Capital Increase, with the intention that the issue price of the preferred shares relative to the issue price of the common shares will reflect the current ratio established for the exchange of common and preferred shares of Oi for common shares of Corpco provided in Item 3.4.1 below. TelPart, AG and LF will assign all of their respective priority rights to Portugal Telecom free of charge.

3.1.6 Based on the result of the subscription orders in the Oi Capital Increase and the ratio of shares issued by Corpco in exchange for Oi shares provided in Item 3.4.1: (a) Portugal Telecom will not be obligated to consummate the Transaction and all other corporate steps described in this MOU if the percentage of the participation of Portugal Telecom in Corpco is equal to or less than 36.6% of the total capital stock of Corpco on a fully diluted basis after giving effect to the merger of Oi shares referred to in Item 3.4.1 and (b) TelPart will not be obligated to consummate the Transaction and all other corporate steps described in this MOU if the percentage of participation of Portugal Telecom in Corpco exceeds 39.6% of the total capital stock of Corpco on a fully diluted basis after giving effect to the merger of Oi shares referred to in Item 3.4.1. If the Transaction is not consummated as provided in this Item 3.1.6, no Party shall be entitled to claim any compensation from the others, except as provided in Item 9.2 below.

3.1.7 The other conditions of the Oi Capital Increase will be set forth in the Definitive Agreements (as defined below).

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3.2.1 PASA will merge with and into AG, EDSP75 will merge with and into LF, and subsequently AG, LF and Bratel Brasil will merge with and into TelPart, and, at the time of this action, AG, LF and Bratel Brasil shall have no assets or liabilities (or will have cash or cash equivalents equal to their accounts payable), except exclusively that (i) AG will hold shares of TelPart and Oi, (ii) LF will hold shares of TelPart and Oi, and (iii) Bratel Brasil will hold shares of AG, LF, TelPart and Oi. The shareholders of AG and LF will receive, as a result of the mergers set forth herein, the shares held by AG and LF in the capital of TelPart, in proportion to the respective number of shares they hold in the merged companies after the conversions and exchanges of debentures set forth in Item 5.1. Changes in the number of shares held in AG, PASA, LF, EDSP75 and TelPart as a result of the conversions and exchanges of debentures set forth in Item 5.1 and 5.2 and these mergers, will not result in any transfer of control of such companies. After these conversions, exchanges and mergers, and in accordance Item 3.4.1, considering the shares of Oi directly and indirectly held by Portugal Telecom, excluding new shares subscribed to in the Oi Capital Increase, Portugal Telecom will be entitled to 554.47 million shares issued by Corpco.

3.2.2 TelPart, at the time of this action, will have no assets or liabilities (or will have cash or cash equivalents equal to its eventual accounts payable), except that TelPart will hold (directly and through Valeverde Participações S.A.) shares of Oi (and goodwill reserves relating to the investment in Oi).

3.3.1 Corpco will take all measures necessary to apply for on the Novo Mercado segment of BM&FBOVESPA.

3.3.2 Corpco will adopt the administrative structure and the corporate governance principles set forth in Item 7 of this MOU, including the election of members of its Board of Directors.

3.4.1 Oi and Corpco will engage in a Merger of Shares (Incorporação de Ações) in which Oi will be converted into a wholly owned subsidiary of Corpco. As a result of the Merger of Shares, each common share of Oi will be exchanged for a newly issued share of Corpco and each preferred share of Oi will be exchanged for 0.9211 newly issued shares of Corpco. The exchange ratios of shares of Oi for newly issued shares of Corpco have been determined based on the parameter of market prices of the shares of Oi in a period of 30 days, which the Parties understand is appropriate. The Merger of Shares of Oi and Corpco will not result in withdrawal rights for shareholders of Oi under art. 137, II of Law No. 6,404/76.

3.4.2 Portugal Telecom and Corpco will engage in a Merger (Incorporação) of Portugal Telecom with and into Corpco, as a result of which Portugal Telecom will cease to exist. The Merger provided for herein (which will be structured as a merger by incorporation of Portugal

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Telecom with and into Corpco in accordance with the laws of Portugal), will be approved by the General Meeting of the shareholders of Corpco in conjunction with the Merger of Shares provided for in Item 3.4.1 and by the General Meeting of the shareholders of Portugal Telecom after the consummation of the transaction referred to in Item 3.1, provided that at the time of the Merger, Portugal Telecom will have no assets or liabilities (or will have cash equivalents equal to its accounts payable), except, exclusively, the shares issued by Corpco. By virtue of the Merger, the shareholders of Portugal Telecom will receive a number of shares of Corpco equivalent to the number of shares of Corpco held by Portugal Telecom immediately prior to the Merger.

The Transaction and its corporate steps described above and, where applicable, the steps set forth in Item 5 below, will be announced simultaneously and are subject to the approval in their entirety by the Prior Meeting of Shareholders under the Shareholders’ Agreements of PASA, EDSP75 and TelPart, executed or amended on January 25, 2011 (the “Existing Shareholders’ Agreements”), and by the shareholders and/or boards of directors of the companies involved, as applicable.

The consummation of each of the steps set forth in this Item 3 and in Item 5 shall be subject to the valid and final consummation of the Oi Capital Increase, as described in Item 3.1, subject to the consummation of the steps subsequent to the Oi Capital Increase, as may be provided in the Definitive Agreements. Thus, subject to fulfillment of conditions precedent that may be contractually established, the steps set forth in this Item 3 and in Item 5 will be undertaken as a single transaction to ensure their full implementation, which will be an essential condition for consummation of the Transaction and the enhancement of the Industrial Alliance.

Portugal Telecom will contribute to Oi, in payment for the shares for which it subscribes in the Oi Capital Increase in accordance with Item 3.1, the shareholding interests held by Portugal Telecom in the companies that hold all of (i) the operating assets of Portugal Telecom, except interests held directly or indirectly in Oi and Contax Participações S.A. and (ii) Portugal Telecom’s liabilities at the time of contribution (the “PT Assets”), which will be identified and subject to appraisal by a specialized firm, whose valuation report will be submitted to the approval of the General Meeting of shareholders of Oi, pursuant to Law No. 6,404/76 (the “Valuation Report on PT Assets”). This transaction will also be subject to approval of the shareholders of Portugal Telecom gathered in General Meeting. This contribution will be made directly by Portugal Telecom or through the contribution of a company wholly owned by it which will hold at the time of the contribution all of the PT Assets.

Portugal Telecom has provided the management of Oi public and other relevant information whose disclosure is not legally restricted, relating to the PT Assets.

Portugal Telecom estimates the equity value of the PT Assets, to be valued for purposes of its contribution to the payment of the Oi Capital Increase, to be in a range of values with a minimum of €1.9 billion and a maximum of €2.1 billion, (the “Estimated Value of PT Assets”), equivalent to, respectively, R$5.8 billion and R$6.4 billion (based on the current exchange rate of 3.0181 reais per Euro).

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Portugal Telecom shall accrue all costs incurred in the Transaction, including any other restructuring costs that should be properly incurred and/or accrued before the verification of the value of the PT Assets that are subject to appraisal.

The Valuation Report on PT Assets will indicate the values in reais of the PT Assets considering the exchange rate of Euros to reais on the date of issuance of the Valuation Report on PT Assets, which shall be the day immediately preceding the publication of the notice of the Extraordinary General Meeting of Oi to consider the Valuation Report on PT Assets, provided that the period between the date of issuance of the Valuation Report on PT Assets and the date of actual payment for the shares of Oi by Portugal Telecom through the contribution of the PT Assets to Oi does not exceed the minimum legal term. If the Valuation Report on PT Assets assigns values on the date of its issuance lower in euros than the Estimated Value of PT Assets considering the conversion rate of Euros to reais on the date of its issuance, Portugal Telecom has the right not to accept the assessed valuation and not to consummate the subscription of shares in the Oi Capital Increase to be paid up by the contribution of the PT Assets. In this case, no other Parties shall be entitled to claim any compensation from Portugal Telecom.

5.1.1 AG and LF will issue, and Portugal Telecom will subscribe for, debentures (i) convertible into shares of AG and LF, in equal numbers, and (ii) exchangeable for preferred shares of Oi held by AG and LF, in equal numbers, in an amount sufficient to pay all indebtedness of AG and LF, including debt owed to BNDES, and pay the subscription price for debentures issued by TelPart as described in Item 5.2 below.

5.2.1 TelPart will issue, and LF and AG will subscribe, in the proportion of 50% (fifty percent) each, for convertible debentures issued by TelPart in an amount sufficient to pay the entire indebtedness of TelPart, including debt owed to BNDES.

Portugal Telecom’s obligation to pay for the debentures issued by AG and LF to be subscribed by Portugal Telecom as described in Item 5.1 of this MOU, and the obligation of AG and LF to pay for debentures issued by TelPart to be subscribed by AG and LF as described in Item 5.2 of this MOU, are conditioned upon, and therefore will only occur after, the valid and final consummation of the Oi Capital Increase, as described in Item 3.1, it being agreed that Portugal Telecom’s obligation to pay for the debentures issued by AG and LF and AG’s and LF’s obligation to pay for the debentures issued by TelPart will be guaranteed at the time of their respective subscription through a pledge of the following shares of Oi held by Portugal Telecom or AG and LF, as appropriate: 1. 252 million shares of Oi, held by Portugal Telecom, to be pledged to AG and LF, 2. 70 million shares of Oi, owned by AG, to be pledged to Telpart, and 3. 70 million shares of Oi, held by LF, to be pledged to Telpart.

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The Parties undertake, following the execution of this MOU, to conduct the business and operations of the companies involved in the Transaction, in particular but without limitation, Oi and the PT Assets, in their ordinary course, refraining from the execution of any act that may prevent or impair the consummation of the Transaction, as well as the continued development of the potential synergies arising from the Industrial Alliance, in accordance with initiatives and workstreams with respect to Oi/PT already underway.

To this end, the Parties shall, under the Industrial Alliance established in 2010, entrust to the current CEO of Oi and President of PT Portugal, SGPS, S.A. (“PT Portugal”), Mr. Zeinal Bava, the complete coordination of the implementation of the Transaction, to be accompanied by a Steering Committee comprised of representatives of the Parties, with the following composition: Amilcar Morais Pires, Henrique Manuel Fusco Granadeiro, José Mauro Mettrau Carneiro da Cunha, Nuno Rocha dos Santos Almeida e Vasconcellos, Otávio Marques de Azevedo and Pedro Jereissati.

Corpco’s bylaws shall provide that its Board of Directors shall be composed of eleven (11) members and eleven (11) alternate members. Members of the Board of Directors of Corpco to be elected in preparation for its listing on the Novo Mercado segment and the Merger of Shares of Oi and Corpco, shall serve for three (3) years from their election or until the General Meeting to examine Corpco’s financial statements for the third fiscal year to end after the end of the year in which the Merger of Shares occurs, whichever occurs last (the “First Board of Corpco”). The First Board of Corpco will be composed of the following members: Alexandre Jereissati Legey, Amilcar Morais Pires, Fernando Magalhães Portella, Fernando Marques dos Santos, Henrique Manuel Fusco Granadeiro, José Maria Ricciardi, José Mauro Mettrau Carneiro da Cunha, Nuno Rocha dos Santos de Almeida, Rafael Luís Mora Funes, Renato Torres de Faria and Sergio Franklin Quintella. Mr. José Mauro Mettrau Carneiro da Cunha and Mr. Henrique Manuel Fusco Granadeiro will assume the positions of President and Vice-President, respectively, of the First Board of Corpco.

Mr. Zeinal Bava, current CEO of Oi and CEO of PT Portugal, will be the CEO of Corpco and its subsidiaries. The Board of Directors of Corpco will meet immediately after its own election and confirm Mr. Zeinal Bava as CEO of Corpco after the consummation of the Transaction, by implementing the steps described in Item 3.4.1 of this MOU.

The Parties shall develop negotiations with a view to achieving the objectives set forth in this MOU, and such negotiations shall be guided according to the dictates of good faith. The Parties shall use their best efforts, within the term of this MOU, or its possible extensions, to obtain all necessary approvals by the governing bodies of Oi and Portugal Telecom, and negotiate and execute the Prior Meeting of Shareholders of TelPart, which will consider all the steps and conditions of the Transaction, including the conditions of the proposed Oi Capital Increase, and the definitive agreements contemplating the measures necessary for implementation of the Transaction and the final consummation of the Industrial Alliance, as set forth in the terms of this MOU (the

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“Definitive Agreements”). In the Definitive Agreements, the Parties shall terminate, and shall release each other under, subject to the consummaton of the Transaction, the Existing Shareholders’ Agreements and other contracts that will be terminated due to the Transaction.

9.1 The completion of the Transaction contemplated by this MOU, including each of the steps mentioned in Items 3 and 5, shall in any event, be subject to cumulative satisfaction of the following conditions precedent, among others that may be necessary or defined:

a) Obtaining the necessary legal and administrative authorizations in Brazil, Portugal and other applicable jurisdictions, particularly from CADE and Autoridade da Concorrência, including approvals and/or registrations with Anatel, ANACOM, the CVM, the CMVM and the SEC, as applicable;

b) Agreement of the Parties to the terms and conditions of the Definitive Agreements, and approval of the terms of the Transaction by the competent governing bodies of each of the companies and their respective shareholders;

c) Obtaining prior approvals from creditors and third parties where required to implement the Transaction, as well as the waivers or consent of creditors of the Parties and companies involved in the Transaction to avoid breaches or defaults under contracts as a result of the Transaction, in the manner to be agreed in the Definitive Agreements;

If any of the above conditions is not satisfied for any reason, none of the Parties will be required to consummate the Transaction contemplated by this MOU, and if the Transaction is not consummated, none of the Parties shall be entitled to claim any compensation from any other Party.

9.2 If the Transaction is not consummated for any reason other than a default by Portugal Telecom of its obligations under this MOU, Oi must reimburse Portugal Telecom for its costs and expenses related to the liability management exercise that have been incurred and documented by Portugal Telecom, up to a maximum value of US$10.0 million.

This MOU will remain in effect until October 1, 2014, unless it is extended by the Parties by written agreement, and will cease to be valid on that date if the Parties do not reach an agreement regarding the subject matter of this MOU. Items 6, 8, 9.2 and 11 through 14 bind and obligate the Parties and shall remain in full force and effect as long as this MOU is in effect, while Item 12 shall remain in full force and effect for a further period of three years from the date of termination of this MOU.

During the term of this MOU, the Parties shall ensure reciprocal exclusivity in relation to the matters contained herein.

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Each of the Parties, their respective officers, directors, collaborators or representatives, agree to maintain the confidentiality of negotiations and discussions undertaken under this MOU, as well as the information to which they have access as a result of the same, except with regard to compliance with applicable law and regulatory standards for securities markets applicable to the Parties and their respective subsidiaries.

Portugal Telecom and Oi shall, immediately after the signing of this MOU, disclose material facts to the market, subject to the terms of the drafts that are attached hereto and made a part of this MOU.

This MOU has been drafted under and will be governed by Brazilian law.

The parties expressly agree that the competent court to settle any litigation or dispute arising from the interpretation or application of this MOU will be the court of the City of Rio de Janeiro, expressly waiving jurisdiction of any other court, regardless of how privileged they are.

And, in witness whereof, the Parties execute this instrument in two counterparts of equal content and form, in the presence of two (2) undersigned witnesses.

Executed in Lisbon, Portugal, this 1st day of October, 2013.

Oi S.A.

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