Highland Capital Urges Motient Corporation Stockholders to Vote for Its Highly Regarded and Experienced Nominees; Criticizes Motient's Board and Management as Poor Managers and Weak Negotiators.

DALLAS -- Highland Capital Management, L.P. announced today that it is mailing the following letter to Motient Corporation (PINK: MNCP) stockholders urging stockholders to elect Highland's eight highly regarded and experienced nominees for Motient's Board of Directors at Motient's Annual Meeting of Stockholders on July 12, 2006. In the letter, Highland also criticizes Motient's Board and management as poor managers and weak negotiators, and explains why it believes Motient's slate will not maximize value for stockholders. The letter also identifies several reasons why Highland strongly opposes Motient's proposed transaction with SkyTerra Communications, Inc. (OTCBB: SKYT).

The text of the letter follows:

July 6, 2006

    Dear Fellow Motient Stockholder:

    We are writing to ask for your support at Motient's upcoming
Annual Meeting of Stockholders on July 12, 2006 to replace Motient's
Board with our eight independent and principled nominees - individuals
who will represent the interests of Motient stockholders first and
foremost.

   WE BELIEVE MOTIENT'S BOARD AND MANAGEMENT HAVE FAILED TO MAXIMIZE
                   VALUE AND WILL CONTINUE TO DO SO

    As of the Friday, June 30, 2006 market close:

    --  Motient's stock price has declined more than 50% since
        February 9, 2005, when Motient monetized Raj Singh's interest
        in MSV by exchanging his interest in MSV for more than 8
        million shares of Motient. At the time, Motient's stock was
        trading at $29.20.

    --  Interestingly, two days later Motient's stock hit its all-time
        high since emerging from bankruptcy. Mr. Singh has been
        selling millions of shares since then.

    --  Seven months later, on September 22, 2005, Motient announced
        its failed roll-up transaction.

    --  Eight months after that, on May 8, 2006, Motient announced its
        proposed transaction with SkyTerra. Motient's stock price has
        dropped nearly 23% since the proposed SkyTerra deal was
        announced.

      VOTE THE GOLD PROXY CARD FOR BOARD MEMBERS WHO WILL WORK TO
                    MAXIMIZE VALUE FOR STOCKHOLDERS

   WE BELIEVE MOTIENT'S BOARD AND MANAGEMENT HAVE PROVEN THEMSELVES
                TO BE BAD MANAGERS AND WEAK NEGOTIATORS

    --  Do you think it shows good business judgment for the Motient
        Board and management to sell a substantial portion of
        Motient's assets without a stockholder vote while facing a
        hotly contested Board election?

    --  Why should Motient shell out up to $80 million in corporate
        taxes and hand control of MSV to SkyTerra without any apparent
        control premium, in exchange for ownership of non-voting
        shares in a lightly traded stock and only minimal SkyTerra
        Board representation? How does Motient expect to pay these
        taxes? And why isn't Motient receiving SkyTerra Board
        representation commensurate with its majority ownership in
        SkyTerra?

    --  Why do Motient's Board and management insist that the only way
        to structure this deal was for it to be taxable to Motient,
        when several months ago they proposed a tax-free
        reorganization to acquire certain outside interests in MSV and
        TerreStar from SkyTerra?

    --  Why haven't the Motient Board and management provided
        stockholders with sufficient information to conduct basic
        cost-benefit analyses about the SkyTerra transaction?

    --  Why are the Motient Board and management apparently using a
        lower valuation for MSV today, when they used a higher
        valuation for MSV when they proposed to buy MSV shares from
        SkyTerra in September 2005, as discussed in our definitive
        proxy statement? Does it make sense to buy high and sell low?

    --  Why do the actions of Motient's Board and management seem to
        favor SkyTerra over Motient's own stockholders?

    --  Do you think it shows good business management and oversight
        by Motient's management and Board to sell Motient's lone
        operating business for only $1 and assumed liabilities? Why
        was management unable to generate a profit from this business?

    --  How can one consider the Motient Board and management credible
        when they call their results over the past four years
        "stellar," results that include:

        --  declining year-over-year revenues;
        --  an increase of more than 130% in SG&A expenses since 2003;
            and
        --  a net loss of $158.4 million for the year ended December
            31, 2005 on revenues of $13.8 million.

    --  If the proposed SkyTerra deal cannot be stopped, can you have
        confidence that the Motient Board and management will
        negotiate a future deal for TerreStar that maximizes value for
        Motient stockholders?

      HIGHLAND'S INTERESTS ARE ALIGNED WITH FELLOW STOCKHOLDERS:
                       MAXIMIZING OUR INVESTMENT

    As one of Motient's largest stockholders, Highland's interests are
aligned with yours. Our sole interest is in maximizing our investment;
and our independent, experienced nominees are committed to serving all
stockholders equally and delivering maximum value as quickly as
possible.

         OUR WELL-RESPECTED DIRECTORS CAN OPEN DOORS TO VALUE

    Our nominees understand the potential future value of Motient's
assets and have the experience and expertise necessary to realize that
value for stockholders. They are leaders in their fields, and include
senior executives with over 115 years of operating experience in the
satellite, wireless, telecom and cable industries, plus individuals
with deep expertise in finance, valuation analysis and corporate
governance.
    Our nominees know Motient's markets and potential partners, and
understand what is necessary to lead the company forward. They are
prepared to hit the ground running, committed to finding the right
strategic alternatives for Motient as quickly as possible and
dedicated to protecting and maximizing your investment.
    Motient stockholders do not deserve to be misled and have their
investment mismanaged by what we believe to be an ineffective and
conflicted Board and management. We urge you to protect your
investment and replace the Motient Board with our eight
highly-qualified and well-respected nominees who are committed to
preserving stockholder value and acting in the best interests of
Motient's stockholders, not themselves or outsiders like SkyTerra.
    To maximize the value of your investment, we urge you to vote FOR
our nominees and proposals by signing, dating and returning the
enclosed GOLD proxy card. If you have previously signed a white proxy
card, you can automatically revoke it by signing, dating and returning
the enclosed GOLD proxy card in the accompanying envelope.

   PROTECT YOUR INVESTMENT: SIGN, DATE AND RETURN THE ENCLOSED GOLD
                           PROXY CARD TODAY

    If you have any questions about our solicitation, or need
assistance in voting your GOLD proxy card, please call our proxy
solicitors, MacKenzie Partners, Inc., Toll-Free at [phone] or
[phone] (call collect). Please see www.ABetterMotient.com for
additional information.

    Thank you for your careful consideration.

    Sincerely,

/s/ James D. Dondero                 /s/ Niles K. Chura
President of the General Partner     Portfolio Manager
Highland Capital Management, L.P.    Highland Capital Management, L.P.

About Highland Capital Management, L.P.

Based in Dallas, with offices in New York and London, Highland Capital Management, L.P. is an SEC-registered investment adviser specializing in credit and alternative investment investing. Highland Capital currently manages over $25 billion in leveraged loans, high yield bonds, structured products and other assets for banks, insurance companies, pension plans, foundations, and high net worth individuals.

IMPORTANT INFORMATION

HIGHLAND STRONGLY ADVISES ALL SECURITY HOLDERS OF MOTIENT TO READ THE DEFINITIVE PROXY STATEMENT AND OTHER DOCUMENTS RELATED TO THE SOLICITATION OF PROXIES BY HIGHLAND AND THE OTHER PARTICIPANTS IN THE SOLICITATION FOR USE AT MOTIENT'S ANNUAL MEETING SCHEDULED TO BE HELD ON JULY 12, 2006. SUCH DEFINITIVE PROXY STATEMENT IS AVAILABLE FOR FREE AT THE SECURITIES AND EXCHANGE COMMISSION'S WEBSITE AT HTTP://WWW.SEC.GOV, AT HIGHLAND'S PROXY WEBSITE AT HTTP://WWW.ABETTERMOTIENT.COM OR BY CONTACTING HIGHLAND'S SOLICITOR, MACKENZIE PARTNERS, INC., AT ITS TOLL-FREE NUMBER: [phone], OR BY COLLECT CALL AT [phone].