WebEx MediaTone Network Expands Audio Conferencing Capabilities With Sonus Solution

CHELMSFORD, Mass., February 7, 2005 - Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions today announced that WebEx Communications, Inc. (Nasdaq: WEBX), a provider of on-demand web meeting applications, is augmenting its WebEx MediaTone Network with a VoIP solution from Sonus, further enhancing WebEx's industry-leading services. WebEx is deploying Sonus' Open Services Architecture (OSA), including the GSX9000TM  Open Services Switch and the Insignus Softswitch, in its data centers to deliver new IP-based conferencing services to its customers.

"More than 12,000 businesses around the world rely on WebEx and the WebEx MediaTone Network, and we required a technology partner that could deliver a solution with the reliability and performance our customers demand," Shawn Farshchi, CIO, WebEx Communications. "As a leader in the VoIP market, Sonus delivered a solution that met all our current requirements and provided the flexibility to support future web meeting applications."

"We are pleased that WebEx selected Sonus to enhance its network and expand its VoIP architecture," said Bert Notini, president and COO, Sonus Networks. "WebEx is a recognized leader in the rapidly growing web meeting applications market, and its decision to augment its existing audio conferencing offering with a Sonus-based solution demonstrates the strength of Sonus' technologies and our ability to provide best-of-breed services to businesses looking for a competitive edge."

"Service providers and enterprises looking to offer new services are turning to VoIP. This new network architecture opens the possibility for the development of more vertical and more customized applications," said Danny Klein, senior analyst at the Yankee Group. "The move by WebEx to migrate its audio conferencing capabilities to IP is significant in that it will enable WebEx to combine content and voice seamlessly, and to develop additional features. As a veteran in the VoIP industry, Sonus is helping to drive the growth of enhanced services such as IP conferencing by providing carrier-class solutions."

About WebEx Communications, Inc.

WWebEx Communications, Inc. is the world's leading provider of on-demand web meeting applications. WebEx applications improve collaboration and increase productivity in sales, support, training, marketing, engineering and product design. The WebEx suite of web meeting applications are built on the MediaTone platform and delivered over the global WebEx MediaTone Network, a network specifically designed for secure, real-time web collaboration. WebEx Communications is based in San Jose, California and has regional headquarters in Europe, Asia and Australia. Please call toll free 877-509-3239 or visit www.webex.com for more information.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. With its Open Services ArchitectureTM  (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking and tandem switching, residential and business access, network border switching and enhanced services. Sonus' voice infrastructure solutions, including media gateways, softswitches and network management systems, are deployed in service provider networks worldwide. Sonus, founded in 1997, is headquartered in Chelmsford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain forward-looking statements regarding future events that involve risks and uncertainties. Readers are cautioned that these forward-looking statements are only predictions and may differ materially from actual future events or results. Readers are referred to the "Risk Factors" section of Sonus' Annual Report on Form 10-K/A dated July 28, 2004 and filed with the SEC, and the "Cautionary Statements" section of Sonus' Quarterly Report on Form 10-Q, dated November 9, 2004 and filed with the SEC, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. In addition, any forward-looking statements represent Sonus' views only as of today and should not be relied upon as representing Sonus' views as of any subsequent date. While Sonus may elect to update forward-looking statements at some point, Sonus specifically disclaims any obligation to do so.

Sonus is a registered trademark of Sonus Networks. Open Services Architecture, GSX9000, Insignus and Sonus Insight are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.