DALLAS, TEXAS, January 28, 2000 - Allegiance Telecom, Inc. (Nasdaq: ALGX) will host a conference call on Wednesday, February 9, 2000, at 9:00 a.m. (ET) with Royce J. Holland, chairman and CEO, C. Daniel Yost, president and chief operating officer, and Thomas M. Lord, executive vice president of corporate development and chief financial officer. Allegiance Telecom will discuss fourth quarter earnings for 1999 and other recent developments. The presentation will be followed by a question and answer session.

If you wish to participate, the dial in number is (800) 946-0783 and confirmation code is 875581. Please dial in 10 minutes prior to the official start to ensure that the call starts promptly.

A replay of the call will be available from noon (ET) Wednesday, February 9, 2000, through midnight (ET) on Wednesday, February 16, 2000. To hear the replay, dial (888) 203-1112 and reference confirmation number 875581.

Allegiance Telecom, Inc. (Nasdaq: ALGX) is a facilities-based competitive local exchange carrier (CLEC) that offers businesses a complete package of telecommunications services, including local, long distance, international calling, high-speed data transmission and Internet services. The Company is targeting 36 major metropolitan areas in the U.S., with its "one-stop shopping" approach. Allegiance Telecom is currently operational in the following 19 markets: Atlanta, Baltimore, Boston, Chicago, Dallas, Detroit, Fort Worth, Houston, Long Island, Los Angeles, New York, Northern New Jersey, Oakland, Orange County, Philadelphia, San Diego, San Francisco, San Jose and Washington D.C. Based in Dallas, the Company's web address is: www.allegiancetele.com.