Red Herring Names Sonus Networks As One of the "Ten to Watch" Latest Honor for Leader in Carrier-Class Voice-Over-Packet Telephony Solutions Recognizes Sonus' Aggressive Growth and Customer Base

WESTFORD, Mass., May 24, 1999 – Sonus Networks Inc., an emerging leader in carrier-class Voice-Over-Packet solutions that fully integrate with the existing public voice network, today announced it has been named as one of Red Herring's "Ten to Watch" for 1999 at the Venture 99 conference at Lake Tahoe, California.

Sonus was one of ten companies selected from a field of hundreds of companies worldwide, based on its successful introduction of the award-winning GSX9000 Open Services Switch, the industry's only "any-to-any" Voice-Over-Packet central office switch that extends the life, scalability, and services potential of today's public voice network.

"We selected Sonus Networks as one of our 'Ten to Watch' because of the company's strategy of long-term growth and its industry leading technology," said John Mecklenburg, managing editor of events for Red Herring. "Sonus has the first high-end Voice-over-Packet carrier switch that's also an open platform for enabling carriers to build new service applications in "Internet Time", allowing differentiation from other carriers and new service revenue growth. Service enablement is a crucial carrier market need, particularly given that carrier revenues from toll minutes continue to fall. Sonus Networks is an exciting voice-over-packet market entrant, and we're looking forward to tracking its growth."

"We are honored and gratified by this important recognition from Red Herring, and view it as both an important validation of our growth strategy, and recognition of the strong market momentum for solutions that will redefine the intelligence and economics of the public network," said Hassan Ahmed, Sonus Networks President and CEO.

The Sonus Networks management team has a distinctly successful track record in delivering carrier grade WAN and telephony solutions. The team's experience in telecommunications, multimedia and data communications gives Sonus distinct advantages in the delivery of packet telephony solutions.

The Sonus Networks' management team is led by Rubin Gruber, Chairman and founder, previously founder of VideoServer (Nasdaq: VSVR), Davox (Nasdaq: DAVX), and Cambridge Telecommunications, acquired by GTE (NYSE: GTE); Hassan Ahmed, Ph.D., President and CEO, most recently Executive Vice President and General Manager of Ascend Communications' (Nasdaq: ASND) Core Systems Division, and previously, Cascade Communications' Chief Technology Officer; Dr. Michael Hluchyj, Vice President, founder and CTO, previously VP and CTO at Summa Four, recently acquired by Cisco (Nasdaq: CSCO), Director of Networking Research at Motorola Codex (NYSE: MOT), and Gary Rogers, previously Senior Vice President of Sales at Security Dynamics (Nasdaq: SDTI) and Bay Networks' Vice President of International Sales, acquired by Nortel Networks Corp. (NYSE: NT).

Red Herring's inaugural "Ten to Watch" list showcases companies in the early stages of development that show promise of growing into global technology leaders. The list accompanies the annual listing of the ``Top 100 Technology Companies'' featuring Red Herring's selection of the top 50 public and top 50 private technology companies of the year. The publication's editorial staff selects the companies for both lists, which are published in the June 1999 issue. The other "Ten to Watch" are Again Technologies, BidCom, Global Sight, Niku, Pixelworks Inc., Qpass, Springfield Project, Third Voice, and Zefer.

About Sonus Networks

Sonus Networks, Inc. is developing and marketing the next generation of carrier-class packet telephony for the new public voice network. Its equipment facilitates the movement of telephony from traditional circuit networks to packet networks, enabling a host of new carrier and end user packet-based services. Sonus Networks was recently awarded the prestigious Hot Startup of the Year Award by Data Communications Magazine, which also awarded the Sonus GSX9000 the Hot Product of the Year Award. Sonus also received the 1999 Investor's Choice Award at Technologic Partners' Network Outlook Conference. Additional information is available at www.sonusnet.com.

About Red Herring Communications

Red Herring Communications, a privately-held San Francisco-based company, is a fully integrated network of media properties connecting and enabling the technology empowered business builders and leaders, ideas and technologies that are shaping and reshaping business today. Red Herring Magazine, Redherring.com, Red Herring TV and Red Herring Events are each a crucial conduit of information, analysis and opinion, between the vision of Silicon Valley and the power of corporate America. More information on Red Herring Communications can be found at www.redherring.com.