Advanced Radio Telecom to Provide High-Speed Data Access to CarrAmerica Buildings Nationwide.

BELLEVUE, Wash.--(BUSINESS WIRE)--July 12, 1999--

Agreement gives Advanced Radio Telecom access to more

than 280 buildings in 14 metropolitan markets

Advanced Radio Telecom Corp. (Nasdaq:ARTT) today announced its agreement with CarrAmerica Realty Corporation (NYSE:CRE) that gives ART access to CarrAmerica's entire portfolio of buildings in 14 major metropolitan areas across the United States, allowing ART to offer high-speed Internet access services to tenant businesses.

CarrAmerica and its affiliates own a controlling interest in approximately 254 operating office properties and have 40 office buildings under construction in key growth markets. These markets include Atlanta, Austin, South Florida, Chicago, Dallas, Denver, Los Angeles/Orange County, Phoenix, Portland, Ore., Salt Lake City, San Diego, San Francisco Bay Area, Seattle, and metropolitan Washington, D.C.

ART currently has signed access agreements with a number of individual CarrAmerica properties in the Phoenix metropolitan area, and plans to acquire additional properties for its build out of 100Mbps Internet access service in Silicon Valley. (see ART press release, June 8, 1999).

"CarrAmerica's commitment to offering its tenants access to the latest technology is a perfect fit with ART's vision," said Henry C. (Harry) Hirsch, ART chairman and CEO. "Combining state-of-the-art infrastructure installed in CarrAmerica's properties with ART's high-speed access service, businesses across the country can enjoy the tremendous productivity benefits of broadband communications."

ART recently announced that Qwest Communications International Inc. (Nasdaq:QWST), and a group of high-tech investment funds syndicate leader Oak Investment Partners, MeriTech Capital Partners, Advent International, Accel Partners, Brentwood Venture Capital, Worldview Technology Partners, Bessemer Venture Capital, Adams Capital Management -- have signed a definitive agreement for a $251 million equity investment that will expedite the deployment of ART's high-speed wireless network. ART plans to build metropolitan-area broadband wireless networks in 40 of the top 50 U.S. markets over the next few years.

"With the explosion of the Internet and data communications, providing access to the broadband, high-capacity networks gives our customers a competitive advantage," said Phil Hawkins, CarrAmerica chief operating officer. "We are committed to providing our tenants with a variety of options to fulfill their data communications needs, and bringing fixed wireless access to the table is an important value-added amenity."

About ART

Advanced Radio Telecom, Corp. (Nasdaq:ARTT), headquartered in Bellevue, Wash., is a provider of broadband wireless access to businesses at speeds up to 100Mbps. ART currently owns and operates metropolitan area networks in Seattle, Portland, Ore., and Phoenix with plans to expand to 40 of the top 50 U.S. markets in the next few years. ART has a nationwide footprint of 38GHz spectrum licenses in the United States, and owns 26GHz and/or 38GHz spectrum licenses in the United Kingdom and several Scandinavian countries. For more information, please visit ART's web site at www.art-net.net.

About CarrAmerica

CarrAmerica owns, develops and operates office properties in 14 markets throughout the United States. The Company is committed to becoming America's leading office workplace company by meeting the rapidly changing needs of its customers with superior service, a large portfolio of quality office properties, extraordinary development capabilities and land positions and, through HQ Global Workplaces, Inc., and certain other affiliates, the availability of executive suites. Currently, CarrAmerica and its affiliates own a controlling interest in a portfolio of approximately 254 operating office properties and have 40 office buildings under development in key growth markets. These markets include Atlanta, Austin, South Florida, Chicago, Dallas, Denver, Los Angeles/Orange County, Phoenix, Portland, Salt Lake City, San Diego, San Francisco Bay Area, Seattle, and metropolitan Washington, D.C.

The above information includes forward-looking statements regarding potential building acquisition and deployment. These statements are not guarantees of future performance. Known and unknown risks, uncertainties, and other factors, including without limitation, failure to consummate the financing transaction, capital requirements and other financial risks, customer demand, technological risks, the ability to meet financing conditions, management of growth, ability to achieve Year 2000 compliance, competition and government regulation may cause actual results to differ materially from the future results implied or expressed in the forward looking statements. Additional information about the most significant of such factors is set forth in ART's most recent annual report on Form 10-K. The Company does not undertake to update or revise its forward-looking statements publicly even if experience or future changes make clear that any projected results expressed or implied herein will not be realized.