Sonus-Certified c-VoBB Solution Delivers IMS-Ready Applications

CHELMSFORD, Mass., December 5, 2005 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced the release of the Sonus-certified Consumer Voice over Broadband (c-VoBB) Solution, the first in a series of integrated IP Multimedia Subsystem (IMS)-ready solutions designed to enable the rapid deployment of next-generation services. Powered by Sonus' award-winning IMS architecture, these solutions provide a standards-based platform for the delivery of multi-media services, fueling increased subscriber growth and profitability for network operators around the globe.

The Sonus c-VoBB Solution is specifically designed to meet the requirements of carriers and Internet Services Providers (ISPs) entering the consumer VoIP market and supports a broad portfolio of IMS-ready applications. This unique solution provides network operators with the ability to deploy innovative, mass-market, IP-based services that offer consumers a differentiated user experience. In today's competitive market place, the delivery of new services is critical to retaining and growing subscriber bases. In addition to traditional telecom service providers, Sonus' c-VoBB offers benefits to emerging service providers seeking solutions to address the upcoming expiration of the Federal Communications Commissions' ruling on negotiated lease rates for access to the Regional Bell Operating Companies' infrastructure.

The Sonus c-VoBB Solution also includes the Sonus Insight Element Management Systems, which allows service providers to integrate a Sonus-based network solution with existing infrastructure for the delivery of enhanced multimedia communications services over high-speed Internet connections. Sonus' c-VoBB solution provides the feature density and flexibility to simplify deployments, allowing network operators to cost-effectively deliver next-generation services to consumers as part of a combined communications package. By selecting the Sonus c-VoBB Solution, network operators are also able to extend their customer base through seamless expansion into new markets and regions.

“The ability to rapidly deliver multi-media services that redefine the way consumers have traditionally thought of telephony communications is critical for service providers in the market today,” said Steve Edwards, chief marketing officer, Sonus Networks. “The Sonus c-VoBB Solution breaks the boundaries of traditional technology platforms by coupling Sonus' proven IMS-ready architecture with a portfolio IP-based services designed for swift deployment in a secure environment.”

The Sonus c-VoBB Solution delivers carrier-class functionality and basic applications, such as voicemail, speed dialing, distinctive ring-tones and regulatory support for features such as emergency services and lawful intercept. Its open, flexible framework also enables service providers to rapidly create high margin service bundles that include future applications such as presence-driven applications, fixed-to-mobile services, and other solutions that leverage the power of IP-based architectures.

To accelerate the time-to-market for these c-VoBB solutions, Sonus Worldwide Services is leveraging its expertise in the design, integration, and deployment of next generation applications. Sonus Worldwide Services has been engaged by some of the world's largest network operators and offers a broad portfolio of services and support capabilities critical for the seamless deployment of advanced IP-based communication applications.

Sonus IMS Architecture

The Sonus c-VoBB Solution includes components from the Sonus IMS architecture, including the Sonus PSX™ Call Routing Server, ASX™ Call Management Server and the Sonus Insight™ Management System. This standards-based services platform is deployed in some of the world's most innovative service provider networks worldwide providing valuable “lifestyle services” such as click-to-talk, ring-back tones, Instant Messaging and telephony integration. Today, Sonus-based networks carry over 15 billion minutes of customer traffic each month and are positioned to support future IP-based services, such as presence-based services or applications that leverage fixed-to-mobile convergence.

Open Services Partner Alliance (OSPA)

In addition to leveraging the Sonus IMS-ready service platform, the c-VoBB Solution takes advantage of components offered through the Sonus (OSPA) program. Founded in 1999, the Sonus OSPA is the industry's largest interoperability program dedicated to driving standards-based interoperability for enhanced applications. During the last six years, the OSPA has gained significant industry momentum, with a membership of over 150 leading independent vendors. Network operators globally have relied on Sonus' comprehensive testing to deploy multimedia IP-based applications that offer consumers new innovative services that meet the demands for today's lifestyles. The Sonus c-VoBB Solution includes some of the industry's leading basic IP services and provides an ideal platform for the rapid deployment of additional revenue-generating, next-generation IMS-based services.

The Sonus c-VoBB Solution is available today. Please contact your Sonus sales person for details on pricing.

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 comprehensive IP Multimedia Subsystem (IMS) solution, Sonus addresses the full range of carrier applications, including residential and business voice services, wireless voice and multimedia, trunking and tandem switching, carrier interconnection and enhanced services. Sonus' voice infrastructure solutions are deployed in service provider networks worldwide. Founded in 1997, Sonus 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, dated March 15, 2005, and the “Cautionary Statements” section of Sonus' Quarterly Report on Form 10-Q, dated November 8, 2005, both filed with the SEC, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. Risk factors include among others: the impact of material weaknesses in our disclosure controls and procedures and our internal control over financial reporting on our ability to report our financial results timely and accurately; the unpredictability of our quarterly financial results; risks associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities litigation against the company. 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, Inc. The Sonus PSX Call Routing Server, ASX Call Management Server and the Sonus Insight Management System are all trademarks of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.