SUPERCOMM 2002 Booth #32316, Hall A3

End-to-End Cable Telephony Solution Allows Operators to Deploy PacketCable Architecture; Sonus Demonstrates Interoperability with Cable Equipment Vendors at SUPERCOMM

WESTFORD, Mass., June 3, 2002 - Sonus Networks (Nasdaq: SONS), a leading provider of voice infrastructure solutions for the new public network, today unveiled the company's SMARRT Cable solution, a next-generation packet voice solution specifically geared to the requirements of cable operators (MSOs). Sonus' SMARRTTM Cable offers a comprehensive and robust cable telephony solution designed for rapid deployment in PacketCable^TM networks. SMARRT Cable is the latest access solution from Sonus; the company also provides the SMARRT Access solution, a complete end-to-end packet voice solution for carriers deploying local voice networks, which is based on the Insignus^TM ASX Access Server.

PacketCable is a CableLabs -led initiative aimed at developing interoperable interface specifications for delivering advanced, real-time multimedia services over two-way cable plant. Built on top of the industry's highly successful cable modem infrastructure, PacketCable networks will use Internet protocol (IP) technology to enable a wide range of multimedia services, such as IP telephony, multimedia conferencing, interactive gaming, and general multimedia applications. Sonus is a PacketCable IPR vendor, and participates in PacketCable Focus Teams and interoperability testing.

"Faced with a mature market for multi-channel video and intense competition from cable alternatives, cable operators are seeking to offer bundled services that include not only entertainment services, but data and voice services," said Terri Griffin, vice president, marketing, Sonus Networks. "Leveraging packet technology already proven in carrier voice networks, Sonus' new SMARRT Cable offers MSOs a comprehensive, PacketCable-based voice solution that delivers the same levels of reliability, voice quality and features of the PSTN, but much more cost-effectively and flexibly than with a circuit-switched architecture."

Sonus' SMARRT Cable is compatible with PacketCable-compliant terminal adapters, CMTSs (Cable Modem Termination Systems) and other PacketCable components. The primary SMARRT Cable components include:

• The Insignus Call Management Server (CMS) manages the cable access network, including CMTSs and MTAs (Multimedia Terminal Adapters) to provide a rich set of residential and business voice services. Designed to telco standards, the Insignus CMS delivers the features and functionality required to be a local service provider, including lawful intercept/CALEA, Local Number Portability (LNP) and emergency services, as well as carrier-class reliability.
• The Insignus Media Gateway Controller (MGC) manages the interface to the PSTN (Public Switched Telephone Network) and provides robust signaling connection to other local and long distance carriers.
• The Insignus SGX SS7 Gateway (SG) provides a link between the SMARRT Cable network and the PSTN SS7 signaling network. Using the SG, the CMS and MGC can exchange call signaling with PSTN switches and access public databases.
• The GSX9000^TM Open Services Switch, an award-winning Media Gateway (MG), provides advanced voice transport capabilities, delivering scalability, performance and integrated international gateway functionality. The GSX9000 can support a single cable system, but is also capable of aggregating PSTN interface traffic from multiple systems for even more cost-effective deployment.
• The Sonus Insight^TM Management System is a comprehensive, web-based management system designed to simplify the operation of packet voice networks. Providing the PacketCable Element Management System (EMS) and Record Keeping Server (RKS) functions, Sonus Insight seamlessly integrates with existing back office systems such as network management, billing and customer care.

In addition to these core infrastructure components, Sonus also incorporates other key access capabilities into the SMARRT Cable solution, such as audio server and voicemail capabilities. The audio server delivers necessary functionality to play network announcements, bridge parties for conferencing and prompt/collect digits for a variety of other services. The voicemail application server enables MSOs to deploy a feature-rich, IP-based voicemail solution. Alternatively, the SMARRT Cable solution can also connect to legacy TDM (time division multiplexing) voicemail applications.

"As one of the most widely deployed vendors in packet voice for the telco market, Sonus is bringing that expertise to the cable market," said Teresa Mastrangelo, senior analyst, Packet Networks & Services, RHK, Inc. "With SMARRT Cable, Sonus offers a comprehensive line of PacketCable-compliant products that apply Sonus' carrier experience to the telephony requirements of MSOs. The cable market represents a significant opportunity for packet voice, and Sonus is strongly positioned to take advantage of this opportunity."

SMARRT Cable Interoperability Demonstration at SUPERCOMM 2002

At the SUPERCOMM 2002 exhibition held June 4-6 in Atlanta, Sonus is conducting live demonstrations of the SMARRT Cable solution working in conjunction with a range of PacketCable-compatible headend and customer premises equipment from the industry's leading cable vendors. In the demonstrations, Sonus is showcasing the interoperability of the SMARRT Cable solution with various CMTSs, MTAs, eMTAs and IP telephones.

The following vendors and products are highlighted in Sonus' booth:

• ADC (Nasdaq: ADCT) with its Cuda 12000 IP Access Switch
• ARRIS (Nasdaq: ARRS) with its Touchstone Telephony Modem eMTA
• Askey Computer Corporation with its RT 155V MTA
• InnoMedia with its Standalone MTA 3328 models, Embedded EMTA 3528, and MTA 3308 IP Phone
• Tellabs (Nasdaq: TLAB) with the Tellabs 2420 Cable Voice Modem
• Thomson multimedia (Paris Euronext: 18453) (NYSE: TMS) with the RCA DHG455 eMTA
• Toshiba with its PCX1100U DOCSIS Cable Modem

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services Architecture (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services. Sonus' award-winning 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 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' Quarterly Report on Form 10-Q, dated May 10, 2002 and 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 adverse effect of recent developments in the telecommunications industry, the weakened financial position of many emerging service providers, Sonus' ability to grow its customer base, dependence on new product offerings, market acceptance of its products, rapid technological and market change and manufacturing and sourcing risks.

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