25 June 1998
Thanks to Anonymous

    American Mobile Provides STU-III Capabilities for Its Satellite
    Communications Products
    June 23, 1998 5:29 PM EDT

    Provides Secure End-to-End Communications That Meet the Security Needs
    of The U.S. Government, Military and Intelligence Agencies

    RESTON, Va., June 23 /PRNewswire/ -- American Mobile Satellite
    Corporation (Nasdaq: SKYC) today announced that all of its Skycell(R)
    satellite communications products now can provide Secure Telephone Unit,
    Type III (STU- III) service, the national security standard for
    encrypting voice and data to ensure secure communications over public

    telephone networks. With American Mobile's new STU-III capabilities,
    government, military, intelligence agencies and law enforcement
    officials have secure, end-to-end voice communications anywhere in North
    America.

    American Mobile's Skycell(R) Satellite Communications Services
    currently offer private secure communications through its built-in
    digital security. However, with its new STU-III capabilities, American
    Mobile will be able to provide end-to-end security over a public
    switched telephone network, meeting the demanding security needs of U.S.
    government agencies.

    "Our new STU-III service allows government users to safely communicate
    sensitive and classified information anywhere in North America," said
    Walt Purnell, president of American Mobile. "When combined with the
    *OmniQuest(TM) satellite terminal, government employees will be able to
    make secure calls from remote locations for fast, mobile
    communications."

    To access Skycell(R) STU-III service, a STU-III Interface Unit (SIU)
    connects to the serial data port of any American Mobile approved mobile
    satellite terminal, such as the OmniQuest. Users then simply plug in a
    standard STU-III telephone into the RJ-11 port on the SIU and they are
    ready to make and receive secure calls from anywhere in American
    Mobile's Skycell(R) coverage area.

    The OmniQuest satellite terminal is manufactured by Mitsubishi
    Electronics and is the smallest and lightest satellite telephone
    available to commercial customers in the U.S. Weighing approximately
    five pounds and about the size of a notebook computer, the OmniQuest
    allows customers to cost-effectively manage their remote operations and
    provides them with reliable emergency back- up communications.

    Skycell Communications Services consist of a unique voice dispatch
    service that facilitates workgroup communications; circuit switched data
    communications; direct dial voice telephony; fax, and STU-III service.

    Skycell STU-III service, will be provided directly by American Mobile.
    The STU-III interface unit is sold separately and will also be available
    directly from American Mobile and authorized Skycell dealers. For more
    information, please contact American Mobile at 1-800-405-6543 or visit
    American Mobile's Web site at www.AmMobile.com.

    American Mobile Satellite Corporation
    American Mobile (www.AmMobile.com) owns and operates an integrated
    terrestrial/satellite network and provides a wide range of mobile
    communication services, including digital voice dispatch, data
    communications, dual-mode mobile messaging, position reporting services,

    and satellite telephone to the continental U.S., Alaska, Hawaii, Puerto
    Rico, the Virgin Islands, and hundreds of miles of U.S. coastal waters.

    American Mobile services are used in the transportation, field service,
    maritime, two-way messaging and telemetry markets. The company's major
    shareholders include Hughes Communications Inc., Motorola, Inc.,
    Singapore Telecom, and AT&T Wireless Services.

    *OmniQuest is a registered trademark of Mitsubishi Electronics America,
    Inc.

    Factors that could cause forward-looking statements in this news
    release to differ materially from actual results are discussed in
    American Mobile Satellite Corporation's Form 10K for the year ended
    December 31, 1997, and other periodic filings the company has made with
    the Securities and Exchange Commission. Copies of the filings are
    available upon request from American Mobile Satellite Corporation's
    investor relations department. SOURCE American Mobile Satellite Corp.

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