BCE Inc.

March 7, 2007

To each of the entities listed below:
Harbinger Capital Partners Master Fund I, Ltd.
Harbinger Capital Partners Special Situations Fund, LP
Stanfield Offshore Leveraged Assets, Ltd.
Motient Corporation MVH Holdings Inc.

Ladies and Gentlemen:

Harbinger Capital Partners Master Fund I, Ltd. (“Harbinger Master”), Harbinger Capital Partners Special Situations Fund, LP (“Harbinger Special Situations”), Stanfield Offshore Leveraged Assets, Ltd. (“Stanfield” and, together with Harbinger Master and Harbinger Special Situations, the “Buyers”), Motient Corporation (“Motient”), MVH Holdings Inc. (“Sub”) and BCE Inc. (“BCE”) have agreed and hereby confirm as follows:

(1) Waiver of Closing Conditions and Closing of Exchange. BCE hereby waives the closing conditions relating to the filing, delivery and effectiveness of the registration statement required by the Exchange Agreement, dated as of January 15, 2007 (the “Exchange Agreement”), among Motient, Sub and BCE. BCE, Motient and Sub each agree that all of the conditions to closing under the Exchange Agreement other than those that by their nature cannot be satisfied except at the closing have either been satisfied or waived. BCE, Motient and Sub agree to cause the remaining conditions to closing under the Exchange Agreement (i.e. delivery of opinions and closing certificates) to be satisfied (and to close the exchange contemplated by the Exchange Agreement) on March 8, 2007 or as soon thereafter as practicable.

(2) Consent to Transfer; Registration Rights Agreement. Motient hereby consents to the transfer of shares contemplated by (3) below. On the date hereof, Motient and the Buyers are entering into a registration rights agreement with respect to the shares the Buyers are acquiring as contemplated by (3) below and other shares of Motient held by the Buyers.

(3) Sale of Shares. Each Buyer agrees to purchase from BCE, and BCE agrees to sell to such Buyer, concurrently with the closing of the exchange under the Exchange Agreement, the number of shares of common stock of Motient set forth opposite its name in the table below for the aggregate purchase price set forth opposite its name in the table below (in each case, US$8.15 per share), payable in cash by wire transfer of immediately available funds to the account BCE specifies to such Buyer prior to the closing.

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Buyer	# of Shares	Aggregate Purchase Price
Harbinger Master	959,715	US$7,821,677.25
Harbinger Special Situations	1,540,285	US$12,553,322.75
Stanfield	2,000,000	US$16,300,000.00

Effective as of the closing of those purchases and sales:

(a) Each Buyer gives the representations, warranties, acknowledgments and understandings set forth in Annex A hereto,

(b) BCE represents and warrants to each Buyer that it has the corporate power and authority to sell to such Buyer the shares then being sold to such Buyer and that it is delivering good and valid title to such shares, free and clear of all liens other than liens created by such Buyer and

(c) Motient and Sub, jointly and severally, hereby make the same representations and warranties to each Buyer that they made to BCE in Article III of the Exchange Agreement, except that for these purposes the representations and warranties contained in Section 3.3 of the Exchange Agreement shall be deemed to be made with respect to the registration rights agreement referred to in (2) above rather than to the agreements referred to in such section.

Motient agrees that the legal opinion and compliance certificate referred to in Sections 6.3 and 6.5 of the Exchange Agreement shall be addressed to each Buyer as well as to BCE.

(4) Filing and Effectiveness of Resale Registration Statement. Motient agrees to file the resale registration statement contemplated by the registration rights agreements it has with BCE and the Buyers as soon as practicable after the date hereof, and to use commercially reasonable efforts to cause that resale registration statement to become effective as soon as practicable thereafter. The resale registration statement will name both BCE and each Buyer as selling stockholders.

* * * *

No party to this letter agreement shall be permitted to assign its rights and obligations under this letter agreement without the written consent of the other parties. This letter agreement shall be governed by and construed in accordance with the laws of the State of New York without regard to the applicable principles of conflicts of law. This letter agreement may be executed in any number of counterparts, each of which shall be deemed an original but all of which together shall constitute one single instrument. Litigation concerning any disputes arising under this letter agreement or the transactions contemplated hereby may be brought only in state or federal courts located in The City of New York. EACH PARTY HEREBY IRREVOCABLY WAIVES ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY SUCH LITIGATION.

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If the foregoing is in accordance with your understanding, please sign and return one counterpart of this letter to us, whereupon this letter will become a binding agreement among the parties that have executed it.

Very truly yours,

BCE INC.