EXHIBIT I
JOINT FILING AGREEMENT
In accordance with Rule 13d-1(k) under the Securities Exchange
Act of 1934, as amended, the persons named below agree to the joint filing on
behalf of each of them of a statement on Schedule 13D dated November 11, 1999
with respect to the Common Stock, par value $.01 per share, of American Mobile
Satellite Corporation, a Delaware corporation. This Joint Filing Agreement shall
be included as an Exhibit to such joint filing. In evidence thereof each of the
undersigned, being duly authorized, hereby executes this Agreement this 11th day
of November 1999.
SINGAPORE TELECOMMUNICATIONS LIMITED
By: /s/ Hoh Wing Chee
-----------------------------------------
Name: Hoh Wing Chee
Title: VP (International Network)
TEMASEK HOLDINGS (PRIVATE) LIMITED
By: /s/ Ong Xxx Xxxxx
-----------------------------------------
Name: Ong Xxx Xxxxx (Ms.)
Title: Vice President/
Company Secretary