Document:

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                                                                   EXHIBIT 10.50

        SECOND AMENDED AND RESTATED PARENT TRANSFER/DRAG ALONG AGREEMENT
        ----------------------------------------------------------------

                                November 12, 2004

                  This SECOND AMENDED AND RESTATED PARENT TRANSFER/DRAG ALONG
AGREEMENT is entered into by and among Motient Corporation ("MOTIENT"), Motient
Ventures Holding Inc. ("MOTIENT SUB"), TMI Communications and Company, Limited
Partnership ("TMI"), TMI Communications Delaware, Limited Partnership ("TMI
Sub"), Mobile Satellite Ventures LP ("MSV LP"), Mobile Satellite Ventures GP
Inc. ("GENERAL PARTNER"), each investor set forth on SCHEDULE I hereto (each, an
"INVESTOR") and each of the Investor's parents set forth on SCHEDULE I hereto
(each, an "INVESTOR PARENT").

         1.       Each of the Investor Parents (other than SkyTerra
                  Communications, Inc. ("SKYTERRA")) hereby represents and
                  warrants to Motient, TMI and each other Investor Parent that
                  it directly owns 100% of the capital stock of its Investor as
                  set forth on SCHEDULE I hereto.

         2.       Motient hereby represents and warrants to TMI and 3924505
                  Canada Inc. ("TMI SUB GP" and together with TMI, the "TMI
                  ENTITIES") and each Investor Parent that it directly owns 100%
                  of the capital stock of MVH Holdings Inc. ("MVH"), which, in
                  turn, directly owns 100% of the capital stock of Motient Sub.

         3.       The TMI Entities hereby jointly and severally represent and
                  warrant to Motient and each Investor Parent that the TMI
                  Entities directly own 100% of the equity interests of TMI Sub.

         4.       SkyTerra hereby represents and warrants to Motient, TMI and
                  each other Investor Parent that it directly owns 100% of the
                  capital stock of MSV Investors Holdings, Inc. ("MSV INVESTORS
                  HOLDINGS"), which, in turn, directly owns 80% of the
                  membership interests of MSV Investors, L.L.C. ("MSV
                  INVESTORS"). The remaining membership interests in MSV
                  Investors are owned by other investors (the "OTHER SKYTERRA
                  INVESTORS"), all of whom have agreed to be bound by the
                  provisions hereof applicable to a Blocker Parent (as
                  hereinafter defined).

         5.       Each Blocker Parent (as defined below) other than SkyTerra
                  hereby agrees that the Other SkyTerra Investors may, without
                  any restriction or limitation imposed by this Agreement,
                  exchange all of their membership interests in MSV Investors
                  solely for shares of common stock of MSV Investors Holding or
                  SkyTerra, in a transaction or series of transactions the
                  ultimate effect of which is that 100% of the outstanding
                  membership interests of MSV Investors is owned solely by MSV
                  Investors Holding.

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         6.       Each Blocker Parent hereby agrees that certain of the Blocker
                  Parents may, without any restriction or limitation imposed by
                  this Agreement, effectuate the Columbia/Spectrum Transfers (as
                  hereinafter defined). For purposes hereof, the
                  "COLUMBIA/SPECTRUM TRANSFERS" means, collectively, the
                  transfer of all limited partnership interests of MSV LP and
                  shares of GP Stock by (i) Columbia Space (QP) II, Inc.
                  ("COLUMBIA QP II") to Columbia Space (QP), Inc. ("COLUMBIA
                  QP"), pursuant to the merger of Columbia QP II with and into
                  Columbia QP; (ii) Columbia Space (AI) II, Inc. ("COLUMBIA AI
                  II") to Columbia Space (AI), Inc. ("COLUMBIA AI"), pursuant to
                  the merger of Columbia AI II with and into Columbia AI; (iii)
                  Columbia Space Partners II, Inc. ("COLUMBIA SPACE II") to
                  Columbia Space Partners, Inc. ("COLUMBIA PARTNERS"), pursuant
                  to the merger of Columbia Space II with and into Columbia
                  Partners; (iv) Spectrum Space Equity Investors IV-II, Inc.
                  ("SPECTRUM IV-II") to Spectrum Space Equity Investors IV, Inc.
                  ("SPECTRUM EQUITY"), pursuant to the merger of Spectrum IV-II
                  with and into Spectrum Equity; (v) Spectrum Space IV Parallel
                  II, Inc. ("SPECTRUM IV") to Spectrum Space IV Parallel, Inc.
                  ("SPECTRUM PARALLEL"), pursuant to the merger of Spectrum IV
                  with and into Spectrum Parallel; and (vi) Spectrum Space IV
                  Managers II, Inc. ("SPECTRUM II") to Spectrum Space IV
                  Managers, Inc. ("SPECTRUM MANAGERS"), pursuant to the merger
                  of Spectrum II with and into Spectrum Managers.

         7.       Each of Motient, TMI, TMI Sub GP and each Investor Parent
                  (each, a "BLOCKER PARENT" and collectively, the "BLOCKER
                  PARENTS") hereby represents and warrants that that certain
                  First Amended and Restated Investment Agreement, dated as of
                  August 8, 2003, as amended (the "INVESTMENT Agreement"), among
                  MSV LP, Motient, TMI Sub and the investors named therein, as
                  amended, the Ancillary Agreements (as defined in the
                  Investment Agreement) and the Transaction Documents (as
                  defined in the Investment Agreement (including this
                  Agreement)) are the only agreements between or among Motient,
                  Motient Sub, TMI, TMI Sub GP, TMI Sub and any of Investor
                  Parents or the Investors relating to the Investment Agreement
                  or the transactions contemplated thereby.

         8.       Each of the Blocker Parents hereby agree, that, subject to the
                  exception contained in Paragraph 9 below, if any of them shall
                  propose to transfer any of its respective interests in Parent
                  Sub, MVH, TMI Sub or an Investor that holds Percentage
                  Interests (as defined in that certain Amended and Restated
                  Limited Partnership Agreement, dated as of November 12, 2004,
                  by and among General Partner and the limited partners named
                  therein (as amended, restated or otherwise modified from time
                  to time, the "LP AGREEMENT")) in MSV LP, as the case may be
                  (each, a "SUBSIDIARY" and collectively, the "SUBSIDIARIES"),
                  owned by such Blocker Parent, such transfer shall be subject
                  to the rights and obligations contained in Section 8.2 of that
                  certain Amended and Restated Stockholders' Agreement, dated as
                  of November 12, 2004 (as amended, restated or otherwise
                  modified from time to time, the "GP AGREEMENT"), by and among
                  the General Partner and the stockholders named therein (the
                  provisions of which are hereby incorporated herein by
                  reference, mutatis mutandis) as if such Blocker Parent were a
                  Limited Partner (as defined in the LP Agreement) of MSV LP and
                  the interests being transferred were Percentage Interests in
                  MSV LP.

                                       2
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         9.       Notwithstanding the previous paragraph, any Investor Parent
                  may, without any restriction or limitation by virtue of this
                  Agreement, transfer up to 10% to any single transferee, or up
                  to 20% in the aggregate, of its interest in an Investor,
                  provided such transferee executes a joinder to this Agreement
                  agreeing to be bound by the provisions hereof applicable to
                  the transferor.

         10.      Each of the Blocker Parents hereby agrees with each other
                  Blocker Parent that if one or more of the Blocker Parents
                  which own Subsidiaries holding, in the aggregate, a majority
                  of the Percentage Interests propose to transfer or exchange
                  (in a merger, stock transfer or otherwise) all of their
                  interests in such Subsidiaries to an unrelated and
                  unaffiliated third party ("BUYER"), such Blocker Parents shall
                  have, with respect to each other Blocker Parent and their
                  respective ownership interests in the Subsidiaries, the rights
                  and obligations contained in Section 8.5(b) of the GP
                  Agreement (the provisions of which are hereby incorporated
                  herein by reference, mutatis mutandis), as if the Blocker
                  Parents were Limited Partners in MSV LP and the Subsidiaries
                  being transferred were Percentage Interests in MSV LP (the
                  "BLOCKER PARENT DRAG ALONG"). The Blocker Parent Drag Along
                  shall be on the same terms as would be obtained by applying
                  such Section 8.5(b) of the GP Agreement, except that the
                  Blocker Parents and their respective Subsidiaries may be
                  required to provide different representations, warranties and
                  covenants to Buyer to the extent reasonably required to
                  reflect the differences in the nature of the interests being
                  transferred (i.e., a transfer of TMI Sub equity interests
                  versus a transfer of Investor capital stock). Without limiting
                  the generality of the foregoing, the Blocker Parent Drag Along
                  shall provide each of the Blocker Parents with the same
                  percentage of the consideration to be received from Buyer as
                  would be obtained by applying Section 8.5(b) of the GP
                  Agreement (i.e., as if Buyer had acquired MSV LP partnership
                  interests directly, and the proceeds of such acquisition were
                  distributed by each Subsidiary to its respective Blocker
                  Parent); PROVIDED, HOWEVER, that if any of the Subsidiaries
                  has any liabilities, then such liabilities shall be taken into
                  account and reduce the consideration to be received by the
                  owners of such entity. Without limiting the foregoing, each of
                  the parties expressly acknowledges and agrees that the most
                  likely method of structuring a sale or disposition of MSV LP's
                  business is not by means of a sale of MSV LP's assets or
                  partnership interests but rather by means of the transfer of
                  the ownership interests in the various entities that hold
                  interests in MSV LP by sale, merger or otherwise and that a
                  merger or series of mergers or similar transaction involving
                  securities of the acquirer or its affiliates may be fully

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                  taxable to TMI and/or TMI Sub GP (and to any other Investor
                  Parent or Other SkyTerra Investor who owns an Investor
                  organized as a limited partnership or limited liability
                  company (a "LLC INVESTOR")) if TMI Sub (or such LLC Investor)
                  were treated as a partnership for U.S. tax purposes while
                  being treated as a tax-free reorganization by others or may
                  otherwise involve tax consequences that are different for, and
                  potentially adverse to, TMI, TMI Sub GP and/or TMI Sub (and to
                  any other Investor Parent or Other SkyTerra Investor who owns
                  a LLC Investor) compared to the other parties to this
                  Agreement if TMI Sub (or a LLC Investor) were treated as a
                  partnership for U.S. tax purposes.

         11.      The Blocker Parents and the Subsidiaries hereby severally
                  agree that, notwithstanding anything to the contrary in the GP
                  Agreement, without the consent ("CONSENT") of a majority in
                  interest of each of the Columbia Investor Group and the
                  Spectrum Investor Group (each, as defined in the GP
                  Agreement), they shall not (i) allow MSV LP or the General
                  Partner to sell or transfer all or substantially all of its
                  assets or (ii) allow any Subsidiary to sell or transfer its
                  interests in MSV LP or the General Partner, if in either
                  event, any stockholder of any blocker C corporation that is a
                  member of the Columbia Investor Group or the Spectrum Investor
                  Group ("STOCKHOLDER") would incur greater tax liability than
                  if such Stockholder had held its ownership interests in MSV LP
                  or the General Partner directly instead of through blocker C
                  corporations ("ADVERSE TAX CONSEQUENCES"). Without limiting
                  the foregoing, the parties acknowledge and agree that under
                  present law, (A) a sale or transfer of the type described in
                  clause (i) above would result in Adverse Tax Consequences, and
                  (B) a sale or transfer of the type described in clause (ii)
                  above would result in Adverse Tax Consequences if either the
                  Columbia Investor Group or the Spectrum Investor Group joined
                  in such sale or transfer on the same basis as the proposed
                  transferor. The parties further acknowledge and agree that a
                  sale or transfer of the type described in clause (ii) above
                  would not result in Adverse Tax Consequences if such sale or
                  transfer is effected pursuant to the terms of Section 8.2(c)
                  or Section 8.2(d) of the GP Agreement and neither the Columbia
                  Investor Group nor the Spectrum Investor Group joins in such
                  sale or transfer. The parties intend that the after tax
                  consequences to the Stockholders in their indirect investments
                  in MSV LP and the General Partner be no different than if the
                  investment by such Stockholders had been made directly in MSV
                  LP and the General Partner by such Stockholders and,
                  accordingly, agree that Consent will not be required if a
                  disproportionate amount of sale proceeds from a sale or
                  transfer of the type described in clauses (i) and (ii) is
                  allocated to the Stockholders or blocker corporations of the
                  Columbia Investor Group and the Spectrum Investor Group, as
                  the case may be, so as to mitigate any Adverse Tax
                  Consequences to the Stockholders and to put the Stockholders
                  in the same after tax economic position (as collectively
                  determined by the Columbia Investor Group and the Spectrum
                  Investor Group) as if such investments had been made directly
                  in MSV LP and the General Partner by the Stockholders instead
                  of through blocker C corporations.

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         12.      Motient and Motient Sub hereby represent and warrant to TMI
                  and the Investor Parents that from and after the date hereof,
                  Motient Sub (i) shall have no assets or liabilities other than
                  the Percentage Interests, the shares of common stock, $0.001
                  par value per share (the "TERRESTAR STOCK"), of TerreStar
                  Networks Inc. owned by it, the shares of common stock, $0.01
                  per share (the "GP STOCK"), of the General Partner owned by
                  it, and the rights and obligations under the Investment
                  Agreement, the Ancillary Agreements, the Transaction Documents
                  and that certain Purchase Agreement, dated as of November 12,
                  2004, by and among MSV LP and Motient Sub and (ii) shall not
                  engage in any business activities other than holding the
                  Percentage Interests, the GP Stock and the TerreStar Stock.

         13.      TMI, TMI Sub GP and TMI Sub hereby represent and warrant to
                  Motient and the Investor Parents that from and after the date
                  hereof, TMI Sub (i) shall have no assets or liabilities other
                  than the Percentage Interests, the GP Stock owned by it, the
                  TerreStar Stock owned by it, and the rights and obligations
                  under the Investment Agreement, the Ancillary Agreements, the
                  Transaction Documents, that certain Purchase Agreement, dated
                  as of November 12, 2004, by and among MSV LP and TMI Sub, that
                  certain Voting Agreement, dated as of November 12, 2004 (the
                  "MSV VOTING Agreement"), by and among TMI Sub and the other
                  investors named therein and a similar voting agreement amongst
                  the same parties to the MSV Voting Agreement (or affiliates of
                  such parties) relating to the TerreStar Stock (the "TERRESTAR
                  VOTING AGREEMENT" and together with the MSV Voting Agreement,
                  the "VOTING AGREEMENTS"), by and among TMI Sub and the other
                  investors named therein and (ii) shall not engage in any
                  business activities other than holding the Percentage
                  Interests, the GP Stock and the TerreStar Stock and performing
                  its obligations under the Pledge Agreement (as defined in the
                  GP Agreement) and the Voting Agreements.

         14.      Each Investor Parent and Other SkyTerra Investor hereby
                  represents and warrants to Motient and TMI that from and after
                  the date hereof, each of their respective Investors shall (i)
                  have no assets or liabilities other than the Percentage
                  Interests, the GP Stock owned by it, the TerreStar Stock owned
                  by it, and the rights and obligations under the Investment
                  Agreement, the Ancillary Agreements, the Transaction Documents
                  and the Voting Agreements and (ii) not engage in any business
                  activities other than holding the Percentage Interests, the GP
                  Stock and the TerreStar Stock and performing its obligations
                  under the Voting Agreements.

         15.      This Agreement shall be governed by and construed according to
                  the law of the State of New York. This Agreement may be
                  executed in any number of counterparts, each of which shall be
                  deemed an original and enforceable against the parties
                  actually executing such counterpart, and all of which, when
                  taken together, shall constitute one instrument.

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         16.      Upon the consolidation (by a series of mergers or otherwise)
                  of MSV LP, the Investors, Motient Sub and TMI Sub into one
                  corporate entity, this Agreement shall automatically
                  terminate, whereupon the restrictions set forth herein shall
                  be replaced by provisions pertaining to the ownership
                  interests in such corporate entity that are substantially
                  identical to those set forth in Sections 8.1 and 8.2 of the GP
                  Agreement. The parties hereto agree to execute such documents
                  or agreements necessary or appropriate to accomplish the
                  foregoing.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

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                  IN WITNESS WHEREOF, the undersigned indicate their agreement
to the foregoing as of the day and year first above written.

                                        MOBILE SATELLITE VENTURES LP

                                        By: Mobile Satellite Ventures GP Inc.,
                                             Its General Partner

                                        By: /S/ RANDY SEGAL
                                           -------------------------------------
                                               Name:  Randy Segal
                                               Title:    Secretary

                                        MOBILE SATELLITE VENTURES GP INC.

                                        By: /S/ RANDY SEGAL
                                           -------------------------------------
                                               Name:  Randy Segal
                                               Title:    Secretary

                                        MOTIENT CORPORATION

                                        By:    /S/ CHRIS DOWNIE
                                           -------------------------------------
                                               Name:  Chris Downie
                                               Title:   CFO

                                        MOTIENT VENTURES HOLDING INC.

                                        By:    /S/ CHRIS DOWNIE
                                           -------------------------------------
                                               Name:  Chris Downie
                                               Title:  CFO

                                        TMI COMMUNICATIONS AND COMPANY,
                                        LIMITED PARTNERSHIP

                                        By:    /S/ RORY MCCORMICK
                                           -------------------------------------
                                               Name:  Rory McCormick
                                               Title:  President

           [SIGNATURE PAGE - A&R PARENT TRANSFER/DRAG ALONG AGREEMENT]

                                       7
<PAGE>

                                          TMI COMMUNICATIONS DELAWARE,
                                          LIMITED PARTNERSHIP

                                          By: 3924505 CANADA INC.,
                                              Its General Partner

                                          By:    /S/ RORY MCCORMICK
                                                 -------------------------------
                                                 Name:  Rory McCormick
                                                 Title:  President

                                          INVESTOR PARENTS:

                                                 /S/ RAJENDRA SINGH
                                                 -------------------------------
                                                 Rajendra Singh

                                                 /S/ NEERA SINGH
                                                 -------------------------------
                                                 Neera Singh

                                          THE HERSH RAJ SINGH EDUCATION TRUST

                                          By:    /s/ Rajendra Singh
                                                 -------------------------------
                                                 Name:
                                                 Title:

                                          THE SAMIR RAJ SINGH EDUCATION TRUST

                                          By:    /s/ Rajendra Singh
                                                 -------------------------------
                                                 Name:
                                                 Title:

           [SIGNATURE PAGE - A&R PARENT TRANSFER/DRAG ALONG AGREEMENT]

                                       8
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                                        COLUMBIA CAPITAL EQUITY PARTNERS
                                        III (QP), L.P.

                                        By: Columbia Capital Equity Partners
                                            III, L.P., as General Partner

                                        By:    /S/ DONALD A. DOERING
                                               ---------------------------------
                                               Name:  Donald A. Doering
                                               Title:  Chief Financial Officer

                                        COLUMBIA CAPITAL EQUITY PARTNERS III
                                        (AI), L.P.

                                        By: Columbia Capital Equity Partners
                                            III, L.P., as General Partner

                                        By:    /S/ DONALD A. DOERING
                                               ---------------------------------
                                               Name:  Donald A. Doering
                                               Title:  Chief Financial Officer

                                        COLUMBIA CAPITAL EQUITY PARTNERS III
                                        (CAYMAN), L.P.

                                        By: Columbia Capital Equity Partners
                                        Cayman) III, Ltd., as General Partner

                                        By:    /S/ DONALD A. DOERING
                                               ---------------------------------
                                               Name:  Donald A. Doering
                                               Title:  Chief Financial Officer

                                        COLUMBIA CAPITAL INVESTORS III, LLC

                                        By: Columbia Capital Equity Partners
                                            III, L.P., as General Partner

                                        By:    /S/ DONALD A. DOERING
                                               ---------------------------------
                                               Name:  Donald A. Doering
                                               Title:  Chief Financial Officer

                                        COLUMBIA CAPITAL EMPLOYEE INVESTORS III,
                                        L.L.C.

                                        By: Columbia Capital III, L.L.C., its
                                            Manager

                                        By:    /S/ DONALD A. DOERING
                                               ---------------------------------
                                               Name:  Donald A. Doering
                                               Title:  Chief Financial Officer

           [SIGNATURE PAGE - A&R PARENT TRANSFER/DRAG ALONG AGREEMENT]

                                       9
<PAGE>

                                       SPECTRUM EQUITY INVESTORS IV, L.P.

                                       By: Spectrum Equity Associates IV, L.P.
                                            Its General Partner

                                       By:    KEVIN J. MARONI
                                              ----------------------------------
                                              Name:  Kevin J. Maroni
                                              Title:  General Partner

                                       SPECTRUM IV INVESTMENT MANAGERS' FUND,
                                       L.P.

                                       By:    KEVIN J. MARONI
                                              ----------------------------------
                                              Name:  Kevin J. Maroni
                                              Title:  General Partner

                                       SPECTRUM EQUITY INVESTORS PARALLEL IV,
                                       L.P.

                                       By: Spectrum Equity Associates IV, L.P.,
                                           its General Partner

                                       By:    /S/ KEVIN J. MARONI
                                              ----------------------------------
                                              Name: Kevin J. Maroni
                                              Title: General Partner

                                      SKYTERRA COMMUNICATIONS, INC.

                                      By:    /s/ Jeffrey Ledey
                                             -----------------------------------
                                             Name:
                                             Title:

           [SIGNATURE PAGE - A&R PARENT TRANSFER/DRAG ALONG AGREEMENT]

                                       10<PAGE>

                                                                   EXHIBIT 10.1

                          CONSOLIDATED PROMISSORY NOTE
                     (The Conrad von Bibra Revocable Trust)

$350,000.00                                              Lake Forest, California
                                                              September 29, 2004

ON DEMAND, for value received, the undersigned, Prism Software Corporation, a
Delaware corporation (the "Company"), promises to pay to the order of the Conrad
von Bibra Revocable Trust (the "Lender"), at 1415 Milan Ave, South Pasadena,
California 91030, or at such other place as the Lender may designate in writing,
the principal amount of Three Hundred Fifty Thousand Dollars and No Cents
($350,000.00), which consists of certain advances listed below. This Note is
also secured by the Security Agreement dated March 27, 2003.

                                    RECITALS:

1.       TERMS OF BORROWINGS. The borrowings (the "Obligations") shall be on the
         following terms and conditions:

         1.1      INTEREST RATE. From October 1, 2004, the Obligations shall
                  bear simple interest at a rate of 8% (eight percent) per annum

         1.2      PAYMENT ON DEMAND. Amounts due under the Obligations shall be
                  paid within three days after receipt of written demand for
                  such amounts from Lender. The Company may, at its option,
                  prepay all or any amount owed. Unless otherwise specified by
                  Lender, any such payment shall be credited to principal and
                  interest accrued upon such principal.

2.       ATTORNEYS' FEES. In the event any judicial proceedings are instituted
         to enforce or interpret the rights and obligations of the Company and
         the Lender under this Note, the prevailing party in such proceeding
         shall be entitled to reasonable attorneys' fees and costs, as well as
         related costs of collection and appeal.

3.       GOVERNING LAW. This Note and all transactions hereunder and/or
         evidenced hereby shall be governed by, construed under, and enforced in
         accordance with the laws of the State of California, without regard to
         any choice of law or conflict of law provisions thereof.

4.       SEVERABILITY. Should any provision of this Note be declared or be
         determined by any court of competent jurisdiction to be invalid,
         illegal or unenforceable, such provision shall be severable from the
         remainder of this Note, and the legality, validity and enforceability
         of the remaining provisions shall not in any way be affected or
         impaired thereby.

5.       SCHEDULE OF ADVANCES.

                    DATE OF         PRINCIPAL
                    ADVANCE          AMOUNT
                  -----------     ------------
                   7/14/2004        40,000.00
                   7/29/2004        35,000.00
                   8/13/2004        40,000.00
                   8/31/2004        40,000.00
                   9/01/2004        40,000.00
                   9/13/2004        45,000.00
                   9/14/2004        15,000.00
                   9/16/2004        45,000.00
                   9/29/2004        50,000.00
                                  ------------
                                   350,000.00
                                  ============

                                             Prism Software Corporation

                                             By: /s/ David Ayres
                                                 ______________________________
                                                 David Ayres, President

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