Sonus Receives Inaugural IMS Technology Award

CHELMSFORD, Mass., July 26, 2005 – Sonus Networks (NASDAQ: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced that it is the recipient of the 2005 Frost & Sullivan Award for Technology Innovation delivered in recognition of the Company's IP Multimedia Subsystem (IMS) architecture. The Frost & Sullivan Award for Technology Innovation is presented to the company that has demonstrated technological superiority within its industry. The recipient is determined following an examination of emerging and existing technology by industry experts.

Frost & Sullivan highlighted several key aspects of the Sonus IMS solution that differentiate it from others in the industry. Specifically, Frost & Sullivan acknowledged Sonus' long standing commitment to the principles governing IMS, noting that today's IMS architecture is similar to Sonus' original solution framework introduced six years ago. Frost & Sullivan also lauded the Company's early efforts to establish an extensive interoperability program that would promote the efficient delivery of next-generation enhanced services. Today, Sonus' Open Services Partner Alliance (OSPA) is the industry's largest interoperability program, and although at the time of the OSPA's founding there was not a formal, standardized platform such as IMS, Sonus developed a SIP-based architecture structured similar to IMS with session control, border management, applications and management layers.

“With all of the buzz about IMS, it is important to remember that its roots are in work done by Sonus. Moreover, standards usually develop based on what has been generally accepted by vendors and carriers in their deployments; therefore, having the IMS architecture be similar to the one offered by Sonus is a statement of validation and respect for the company,” said Lynda Starr, Senior Industry Analyst, Frost & Sullivan. “To become fully IMS-compliant, Sonus customers will need only to upgrade the software on their existing Sonus architecture. No other vendor comes as close to IMS-compliance.”

“From day one, Sonus focused on developing an architecture that would enable network operators to create new revenue streams and to rapidly deploy innovative multi-media services with rapid time to market cycles. Sonus' commitment to this vision allows wireline and wireless providers to leverage the disruptive force of broadband, and offers a profound change in the delivery of communication services,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “We're honored that Frost & Sullivan has acknowledged Sonus' unique place in the market, and we're proud to receive the 2005 Award for Technology Innovation.”

Sonus' IMS solution allows customers to seamlessly comply with the developing IMS standards and to maximize their investments by delivering converged multimedia services over their existing Sonus architecture. The Sonus IMS solution builds on the proven benefits of Sonus' architecture, which has been deployed in service provider networks for nearly six years and today supports an estimated 13 billion minutes of traffic per month. Key components in the Sonus IMS solution include its existing products: the GSX family Open Services Switch (MGCF, P/I-CSCF), PSX Call Routing Server (BGCF), SGX Signaling Gateway (SGW), ASX Call Management Server (SIP-AS) and Insight™ Management Systems. The Company also recently introduced its IMX Application Platform that further extends its service creation capabilities in an IMS environment. In Q4, Sonus will begin shipping two new components to further extend the flexibility of its IMS architecture: the SRX Serving-Call Server Control Function (S-CSCF) and the HSX Home Subscriber Server (HSS) product.

About the Frost & Sullivan Award for Technology Innovation

The Frost & Sullivan Award for Technology Innovation is presented to the company that has demonstrated technological superiority within its industry. This Award recognizes the ability of the company to successfully develop and introduce new technology, formulate a well-designed product family, and make significant product performance contributions to the industry.

About Sonus

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. With its Open Services Architecture^TM  (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking and tandem switching, residential and business access, network border switching and enhanced services. Sonus' 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 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 May 9, 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. In addition, 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. Open Services Architecture, GSX9000 and Insignus are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.