Sonus Networks Joins Industry Leaders in International Softswitch Consortium

Founding Member in Alliance to Accelerate IP Voice and Multimedia Applications

WESTFORD, Mass., July 14, 1999 – Sonus Networks, an emerging leader in carrier-class packet telephony solutions, today announced that it has joined the International Softswitch ConsortiumSM as a founding member of the Consortium. The Softswitch Consortium is the first group to focus exclusively on worldwide compatibility and interoperability of multimedia IP networks and their interconnection with other networks such as the public switched telephone network. The Consortium will also be a catalyst in stimulating independent software vendors to develop value-added services for service providers and network users.

"With our Open Services Architecture^TM and Packet Telephony suite, Sonus provides an open, standards-based platform upon which carriers and third parties can rapidly develop and deliver innovative new services," said Rubin Gruber, chairman and founder, Sonus Networks. "Sonus looks forward to taking an active role in the Consortium to promote standards that will further the deployment of IP telephony solutions and services."

Benefits to members include access to an interoperability test lab, direction of specification development, early use of reference software implementations and more. The Consortium will be holding its first annual meeting on July 21, 1999 in Santa Clara, California, and will elect the group's Board of Directors and Technical Advisory Council.

Other members of the International Softswitch Consortium include: Alcatel, Aspect Telecommunications, BroadSoft, Castle Networks (a Unisphere Solutions company), Cisco Systems, Enron Communications, Ericsson, Hewlett-Packard Company, Iperia, Inc., ipVerse, Inc., Level 3 Communications, Inc., Nokia, NorthPoint Communications, NTT, pulver.com, Rhythms NetConnections Inc., SALIX Technologies, Inc., Sonus Networks, Sun Microsystems, Sylantro Systems Corporation, Telcordia Technologies, Inc. (formerly Bellcore), Transmedia, Vertical Networks and Vovida Networks. For more information on the Consortium, visit the organization's Web site at http:\\www.softswitch.org.

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 Sonus Packet Telephony suite and Open Services Architecture (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. Its management team has developed and introduced many of the industry's most widely used carrier solutions, and has led organizations such as: Ascend Communications, recently acquired by Lucent Technologies (Nasdaq: LU); Summa Four, recently acquired by Cisco Systems (Nasdaq: CSCO); Bay Networks, recently acquired by Northern Telecom (NYSE:NT); and VideoServer (Nasdaq: VSVR).

Sonus was named one of Red Herring's "Top Ten to Watch" companies and awarded Data Communications magazine's prestigious Hot Startup of the Year and Hot Product of the Year awards. Sonus was also recognized by Technologic Partners with the Investor's Choice award, and was named a finalist for "Most Promising New IP Technology" at the 1999 SUPERQuest awards. Additional information is available at: http://www.sonusnet.com .