Sonus Networks and Motorola Demonstrate Voice Over Wireless Broadband At Fall VON 2005

Industry Pioneers Team to Deliver VoIP over Wireless Broadband

CHELMSFORD and BOSTON, Mass., September 19, 2005 - Today at the Fall VON 2005 Conference, Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, announced that it is showcasing its voice over wireless broadband capabilities with Motorola, a global leader in the wireless communications and mobility industry. Sonus is demonstrating its wireless VoBB solution using Motorola's Canopy™ wireless broadband system to highlight how service providers globally can deliver the benefits of VoIP over a wireless broadband platform. In its booth (#708), Sonus is conducting live demonstrations of Voice over pre-WiMAX services using the GSX™ family, the ASX™ Access Server, PSX™ Call Routing Server, SGX™ Signaling Gateway and Motorola's Canopy wireless broadband system.

“Voice over wireless broadband offers consumers and network operators alike an extraordinary value proposition. It eliminates the expensive infrastructure costs associated with establishing last-mile, wired connectivity to the home, while giving consumers access to reliable, high speed, robust voice and data services,” said Hassan Ahmed, chairman and CEO of Sonus Networks. “In addition, by leveraging an IMS-based core voice over broadband network architecture, service providers have a unique platform that not only allows a differentiated consumer experience today, but also establishes a framework for future services based on fixed-mobile convergence.”

The convergence of two industry trends is driving the demand for voice over wireless broadband services. First, driven by cost-effective pricing plans and enhanced features, both consumers and enterprises globally are continuing to adopt VoIP for their primary communication service. At the same time, WiMAX is growing in popularity as a key broadband access technology for businesses, residences and public areas. Delivering voice services over WiMAX networks is a natural extension of the Sonus VoBB solution. By deploying Sonus' VoBB solutions and the Motorola Canopy transport infrastructure, service providers are able to architect a carrier class network that meets the growing demand for fixed and mobile wireless broadband services. Available for deployment today, the Sonus wireless VoBB solution is ideally suited for Internet Service Providers (ISPs) and other network operators aiming to enter the rapidly growing wireless services market.

“Carriers, ISPs, and enterprises are eagerly embracing wireless solutions to address rapid network deployment needs, particularly in those areas where building physical connections are expensive or challenging. The Canopy platform is designed to deliver cost-effective, reliable and high-speed Internet access in a wireless environment,” said Tom Gruba, director of marketing for Motorola's Canopy wireless broadband business. “Motorola is committed to demonstrating the power of voice over wireless broadband by ensuring that it works seamlessly with solutions offered by companies like Sonus Networks.”

Sonus' VoBB solution delivers basic local area calling features as well as advanced IP-based functionality over broadband technologies, providing a lower-cost and flexible alternative for residential and enterprise telephone services. Features and services provided include caller ID, call waiting, 3-way calling, call hold, voicemail, unified messaging and more. Motorola's Canopy solutions include point-to-point and point-to-multipoint configurations that can span distances up to 15 miles in a multipoint configuration and up to 40 miles in a Point-to-Point configuration. Extending the reach of the Sonus VoBB solution with wireless broadband, network operators can increase market opportunities to offer consumers innovative next-generation services with a cost effective pricing structure.

“Broadband wireless will be critical in markets worldwide, making it economically feasible for network operators to move into new markets and make broadband more ubiquitous. The result, however, will be increased competition throughout the broadband industry, and network operators will have to employ new approaches to distinguish themselves in the market," said Lindsay Schroth, senior analyst with The Yankee Group. "Voice over broadband wireless powered by two industry front-runners like Motorola and Sonus could be a strategic way for network operators to set themselves apart and win favor with end-users.”

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 of U.S. 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 August 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.

The information in this press release is for informational purposes only and is subject to change at Sonus' sole discretion without notice. Sonus has no obligation or commitment to develop or deliver any future release, upgrade, feature, enhancement or function described in this release. The information is provided “AS IS,” with all faults, and without any warranties whatsoever, express or implied, including, but not limited to, warranties of merchantability, performance, or fitness for a particular purpose.

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