Industry Leader Redefines Convergence for Next Generation Networks

CHELMSFORD, Mass., and CHICAGO, IL, June 07, 2005 – Today at SUPERCOMM 2005, Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, announced that it is delivering industry-leading solutions that will enable wireline and wireless service providers to realize the benefits of an IP Multimedia Subsystem (IMS) architecture. The Sonus IMS solution allows customers to seamlessly and cost effectively comply with the developing IMS standards and to maximize their investment by delivering converged multimedia services over their existing Sonus architecture.

“Today's service providers are tasked with the significant challenge of building new revenue streams, improving margins, and attracting new users. Converged networks were originally viewed simply as a way to reduce operating expenses, but the real potential for service providers lies in the rollout of innovative multimedia services,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “IMS is the industry's first framework that allows wireline and wireless operators to leverage the disruptive force of broadband, breaking down the former barriers to service delivery and opening the door for the delivery of new services. The power of IMS is that it allows for a truly presence-enabled network and represents a profound change in the way service providers offer communication services.”

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 approximately 12 billion minutes of traffic per month. Key components in the Sonus IMS solution include its existing products: the GSX family, PSX, SGX, ASX and InsightÔ Management Systems. In a related announcement, the Company also launched its new IMX Application Platform (see Sonus' press release “Sonus Networks Unveils New Multimedia Application Platform for Next Generation Services”) that further extends its service creation capabilities in an IMS environment. Additionally, by separating its existing product capabilities into discrete software modules through the introduction of the SRX and HSX, (see product detail below) the company is extending its ability to offer IMS compliant solutions that enable new deployment scenarios. The Sonus IMS solution delivers the features and protocols necessary to support immediate revenue-generating solutions and provides a path to an all-IP IMS network.

Developed by the 3rd Generation Partnership Program (3GPP), IMS is rapidly emerging as the standard way to build next-generation multimedia networks in both fixed and mobile environments. It enables network operators to converge voice, video and other multimedia services to deliver innovative and compelling bundled solutions to consumers. Designed to standardize the delivery of IP services, IMS defines an architecture that is distributed and supports interoperability among network components. The IMS architecture substantially mirrors the Sonus-built networks currently deployed and in service with Sonus' customers across the globe.

“Global Crossing was one of the world's first service providers to embrace the benefits of a VoIP architecture. We selected Sonus as our network partner in 1999 not only because of their strong product capabilities, but also because their architecture and solutions provided a foundation for the future growth of our IP network,” Anthony Christie, Global Crossing's chief marketing officer. “As a result, Global Crossing today has one of the world's largest IMS-ready networks, providing a simplified, cost-effective solution for customers moving towards new converged IP services.

IMS has emerged as the prevailing standard that uniquely addresses several key business drivers across all types of network operators looking to take advantage of the benefits of an all-IP converged network. With the proliferation of communication devices that operate over fixed and mobile voice and data networks, consumers face increased choice and complexity. By consolidating services on these devices to a single infrastructure, network operators benefit from the ability to deliver more comprehensive, streamlined services. With Sonus' IMS solutions, service providers are able to deliver integrated services over mobile, WiFi and wireline networks providing service differentiation and reduced time-to-market. Further, wireless operators can implement Sonus' proven Gateway Mobile Switching Center (GMSC) solution in their 2G and 2.5G networks today and seamlessly migrate to an IMS-compliant wireless voice network in the future. Sonus' wireless solutions deliver the features and protocol support necessary for rapid deployment in GSM, CDMA, TDMA and 3G wireless network environments.

With the Sonus IMS solution, network operators are able to deliver enriched communication services and fixed-mobile convergence on their existing Sonus architectures. Essential to a successful IMS deployment is the ability for elements within the network to communicate with each other using Session Initiation Protocol (SIP). Sonus has been deploying networks using SIP for over four years and has established the industry's largest VoIP interoperability program the Open Services Partner Alliance (OSPA). Today, some of the world's largest service providers rely on Sonus to test the SIP capabilities of others in the industry.

"Sonus has always delivered distributed VoIP solutions based on SIP, making the transition of its product portfolio into conformance with the IMS architecture smooth and straightforward," says Joe McGarvey, senior analyst, Current Analysis. "Leveraging its SIP roots, Sonus holds an advantage over competitors that must develop crucial IMS functional modules from scratch."

SRX and HSX Detail

Today, Sonus introduced the SRX and HSX products to its IMS product family. The SRX provides streamlined multimedia capabilities when customers choose to deploy a discrete Serving- Call Server Control Function (S-CSCF), creating a central coordination point for all SIP sessions. Leveraging the functionality already available today, Sonus will be offering the SRX as a separate software product in the fourth quarter of 2005 to allow for further architectural flexibility. The HSX is an evolution of Sonus' centralized subscriber management capabilities that enables service providers to deliver device independent multimedia services. The HSX Home Subscriber Server (HSS) will also be available in the fourth quarter of 2005.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. 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.

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.

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.