Revenue Growth of 1205% Puts Company On Top

DALLAS, TEXAS, June 9, 1999 -The Dallas Business Journal named Allegiance Telecom, Inc. (Nasdaq: ALGX) the fastest growing high-tech company in the Dallas Metroplex in their annual "Fast Tech 50" supplement issue, ranking regional companies by revenue growth rates from 1997-1998.

The "Fast Tech 50" profile on Allegiance noted the Company's seasoned management, the over $1 billion in raised capital, its aggressive nationwide strategy and its conservative balance sheet as factors for the Company's rapid growth and success. Allegiance currently employs 460 people in the Dallas headquarters and over 1,000 employees nationwide.

Founded in August 1997, Allegiance Telecom 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 24 major metropolitan areas in the U.S. with its "one-stop shopping" approach. Allegiance is currently operational in 14 markets, including Atlanta, Boston, Chicago, Dallas, Fort Worth, Houston, Los Angeles, New York, Northern New Jersey, Oakland, Philadelphia, San Francisco, San Jose and Washington D.C.

For full text of the "Fast Tech 50" article, see the "In the News" section of the Company's web site at www.allegiancetele.com. Allegiance is a facilities-based CLEC headquartered in Dallas, Texas. Allegiance's common stock is traded on the Nasdaq National Market under the symbol ALGX.

NOTE TO EDITOR: Royce Holland, chairman and CEO of Allegiance Telecom, was one of the original founders of MFS Communications Company, the first major competitor to the Bell System. As president of MFS, Holland was an industry leader in developing the competitive provisions of the Telecommunications Act of 1996, which opened the local exchange market to competition throughout the U.S. Under Holland's leadership, MFS grew from a privately held start-up operation to one of the Nasdaq 100 Index companies with annual revenue of approximately $1 billion and a market value of approximately $13 billion.