Latest Accolade Highlights Sonus' Emerging Leadership Position in Dynamic Market

WESTFORD, Mass., August 25, 1999 - Sonus Networks today announced that it has been named by Telecom Business^TM magazine to the publication's "Top 500" list, which recognizes 1999's most dynamic competitive telecommunications companies. Compiled over a three-month period, the "Top 500" is awarded by the editors of Telecom Business to the companies expected to play crucial roles in shaping the future of today's competitive telecom marketplace.

"We're very pleased to receive the "Top 500" honor from Telecom Business," said Hassan Ahmed, president and CEO of Sonus Networks. "This industry designation underscores Sonus' critical role in facilitating the movement of telephony from circuit networks to packet networks, and the development of innovative applications for integrated voice and data services."

An emerging leader in carrier-class packet telephony solutions, Sonus will be showcased in the October issue of Telecom Business. Award winners also received special recognition at the Telecom Business '99 New York Conference & Expo, August 23-25, at the Jacob K. Javits Convention Center. A complete list of the Top 500 will be available on the Telecom Business Web site at www.telecombusiness.com.

"The companies selected to the Telecom Business Top 500 have positioned themselves on the cutting-edge of this rapidly changing industry. They are the movers, shakers and decision makers in the new competitive telecommunications marketplace," said Telecom Business publisher Marc Ostrofsky. "These companies represent every aspect of the telecom industry from software and equipment to carriers and cable companies. They have either established new and important trends in the industry or displayed the ability to take the converged telecom market to the next level."

About Telecom Business Magazine

Telecom Business magazine is the most comprehensive and widely read publication dedicated solely to the "new" competitive telecommunications industry - CLECs, Data CLECs, long distance providers, resellers, ISPs & IP telephony providers, integrated service providers, cable and utility companies and other next-gen network service providers. For information on Telecom Business '99 New York or Telecom Business magazine, call 1-800-717-7469 or visit the Web site at www.telecombusiness.com.

About Sonus Networks

Sonus Networks, Inc. is delivering a new class of carrier solutions that enable the movement of telephony to converged packet networks, and the development of a new generation of innovative voice and data services. The award-winning Sonus Packet Telephony suite and Open Services Architecture^TM (OSA) cut the time-to-market for competitive new service products from years to weeks, allowing carriers and third-party developers to sustain and expand marketshare, and build important new revenue streams. Its highly scalable products fully interoperate with and extend the life and utility of today's public network. Sonus, founded in 1997, is headquartered in Westford, Massachusetts and is privately held. Additional information is available at: http://www.sonusnet.com.