Companies to Demonstrate IMS-Based Voice Services at 2005 Fall VON Conference

BOSTON, Mass., September 20, 2005 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of voice over IP (VoIP) switching infrastructure solutions, and AOL today announced that they are working together to deliver industry leading IMS solutions enabling advanced IP communications over broadband and mobile networks. IP Multimedia Subsystem ("IMS") enables mobile and converged service providers to offer their subscribers multimedia services, built upon Internet applications, services and protocols. Sonus and AOL have pioneered their solution architecture by combining Sonus' IMS-based architecture and AOL's proprietary technology and expertise in presence-driven communications applications to offer a unique foundation for the next-generation of enhanced consumer voice services.

The first results of this collaboration are at the foundation of AOL's new VoIP service, TotalTalk. The architecture will enable AOL to rapidly develop and deploy new features for their suite of voice and instant messaging products that integrate multimedia and voice services with real-time communications. AOL's TotalTalk is the first IMS-based consumer voice product to launch in the U.S.

"These IMS solutions open the door for network operators globally to deliver a new unique experience to each individual customer that encompasses multiple end-user devices," said Hassan Ahmed, CEO of Sonus Networks. "Our solutions are ideally suited for network operators that are committed to rolling out a new generation of communication services that will change the way people interact, and AOL already has a long and distinguished history of doing just that."

"Our goal is not just to build another phone service, but to harness the power of the IMS architecture to rapidly deploy next-generation communications services that integrate voice, instant messaging, and video," said Ragui Kamel, Senior Vice President of Voice Services for AOL, Inc. "By teaming with Sonus Networks and investing in the right infrastructure, we continue to deliver on AOL's longstanding leadership in improving and innovating communications online."

Sonus will be offering a sneak preview of TotalTalk in their Fall VON Exhibit, booth # 708.

About America Online, Inc.

America Online, Inc. is a wholly owned subsidiary of Time Warner Inc. (NYSE: TWX). Based in Dulles, Virginia, America Online is the world's leader in interactive services, Web brands, Internet technologies and e-commerce services.

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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