New Interactive Voice Portal Simplifies Consumer VOIP Services

CHELMSFORD, Mass., December 12, 2005 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, announced today the availability of the Sonus Voice Portal, an interactive voice response system for managing consumer voice profile data. By deploying the Sonus Voice Portal, network operators empower their customers to personalize their voice service, independent of their location, through a straight-forward, voice-activated menu designed to deliver a highly customized end user experience.

The Sonus Voice Portal is the first application created with and managed by Sonus' recently released IMX application platform, a web-based multimedia environment that enables wireline and wireless service providers to rapidly develop, integrate, launch, and manage enhanced telecommunication applications and services. The Sonus Voice Portal manages the preferences for a wide variety of residential services delivered by the Sonus ASXTM Call Management Server such as speed dialing, call forwarding, three way calling, and nuisance call blocking. Jupiter Telecommunications Co., Ltd. (J:COM) is the first Sonus customer to embrace the expansive capabilities of the Voice Portal application.

“The Sonus Voice Portal is just the first of a number of new applications that leverage the power of the Sonus IMX application platform to reshape today's communications experience. The opportunities are limitless,” said Mike Hluchyj, chief technology officer, Sonus Networks. “With the IMX as a key piece of the network, service providers have the ability to experiment with innovative new services and introduce the solutions most in demand by consumers. The Sonus Voice Portal is instrumental, as it allows subscribers to manage these services on the move, delivering a uniquely customized and personal experience.”

The Sonus Voice Portal is currently available. For information and pricing, contact your Sonus sales representative.

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. All other company and product names may be trademarks of the respective companies with which they are associated.