Carrier Has Deployed Sonus Voice Solutions in Eight U.S. Markets to Deliver Dial-up Internet Access; Business-Class Voice Services to Follow

WESTFORD, Mass., April 9, 2001 – Time Warner Telecom Inc. (Nasdaq: TWTC), a leader in providing local and regional optical broadband networks and services to business customers, and Sonus Networks (Nasdaq: SONS), a leading provider of voice infrastructure solutions for the new public network, today announced that Time Warner Telecom has deployed Sonus' packet telephony product family, including softswitches and media gateways, in eight markets throughout the United States. Time Warner Telecom is now delivering revenue-generating traffic over those networks. 

"We are pleased with the progress that we are making with Sonus in rolling out our next-generation service delivery architecture," said Mike Rouleau, Time Warner Telecom's senior vice president, marketing and business development. "Our Sonus-based network provides a platform through which we meet our immediate and future requirements for Internet dial-up traffic, and with the expectation that it will allow us to deliver a wide range of enhanced voice and data services in the future."

Time Warner Telecom selected Sonus in the third quarter of 2000 as one of its primary suppliers for voice infrastructure solutions to deliver business class telephony services and Internet 'dial tone.' At that time, Time Warner Telecom began installation of Sonus' range of packet voice solutions, as well as Riverstone Networks' RS series of switch routers. Using the combined Sonus/Riverstone solution, Time Warner Telecom has rapidly expanded its packet telephony footprint to eight markets throughout the U.S. The Sonus/Riverstone systems have been deployed in San Diego, Calif.; Austin, Texas; Binghamton and New York, N.Y.; Cincinnati and Columbus, Ohio; Indianapolis, Ind.; and Milwaukee, Wisc.

Time Warner Telecom sought a complete packet telephony solution last year that would allow the carrier to achieve the highest levels of scalability, performance, and reliability. Through a reseller arrangement, Sonus teamed with Riverstone to provide Time Warner Telecom with a robust, NEBS Level 3-certified core network system, comprising Sonus' GSX9000TM Open Services Switch, PSX6000TM Softswitch, SGX2000TM SS7 Signaling Gateway and the Riverstone RS series of switch routers. This combination of products enables Time Warner Telecom to deploy large switch sites, rapidly and cost-effectively, each capable of handling more than 100,000 telephone calls. 

Time Warner Telecom is initially leveraging the Sonus-based network to augment its existing Class 5 circuit switches and offload modem-generated Internet traffic from its voice network. Time Warner Telecom also plans to use the Sonus infrastructure to deliver traditional local and long-distance services, as well as new voice over IP-based services such as unified communications, single number service, call centers, and more. 

"Time Warner Telecom is recognized as a leading player in the broadband communications industry, and the innovative network we're building together will enable them to further raise the bar for competitors," said Hassan Ahmed, president and CEO, Sonus Networks. "We look forward to continuing our close collaboration with Time Warner Telecom and helping them to deliver leading-edge products and services to their business customers."

Time Warner Telecom plans to continue to roll out the Sonus packet voice infrastructure solutions in select markets.

About Time Warner Telecom

Time Warner Telecom Inc., headquartered in Littleton, Colo., builds local and regional optical networks and delivers "last-mile" broadband data, dedicated Internet access and voice services for business. The company currently serves customers in 39 U.S. metropolitan areas. Time Warner Telecom expects to begin offering service in Denver, Chicago, Atlanta, Minneapolis and Columbia, S.C. in 2001. Please visit http://www.twtelecom.com for more information about Time Warner Telecom.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice infrastructure products for the new public network. Sonus' solutions enable service providers to deploy an integrated network capable of carrying both voice and data traffic, and to deliver a range of innovative, new services. The Sonus Open Services Architecture(TM) (OSA) and award-winning Packet Telephony suite cut the time-to-market for competitive new service products, allowing carriers and third-party developers to 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 embodies in its management and staff decades of experience in developing carrier-class voice, data and multimedia solutions for implementation in the world's largest networks. Sonus, founded in 1997, is headquartered in Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain projections or other forward-looking statements regarding future events or the future financial performance of Sonus 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 Sonus' Annual Report, dated March 28, 2001, and associated Registration Statement on Form 10-K, filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. These risk factors include, among others, the Company's ability to grow its customer base, dependence on new product offerings, market acceptance of its products, rapid technological and market change, integration risks relating to the acquisition of telecom technologies and manufacturing and sourcing risks.

GSX9000, PSX6000, SGX2000 and Open Services Architecture are trademarks of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.