SONUS NETWORKS SUPPORTS THE RESEARCH AND DEVELOPMENT OF NEXT GENERATION NETWORKS IN THE SLOVAK REPUBLIC

WESTFORD, MA and STAINES, UK., June 5, 2008 – Sonus Networks, Inc. (Nasdaq: SONS), a market leader in IP
communications infrastructure, today demonstrated its commitment to the
development of the Eastern European telecommunications industry by
providing IP infrastructure hardware and software to the Zilina
Institute of Next Generation Networks (INGN) in the Slovak Republic.
The INGN, which is 66 per cent owned by Slovak Telekom works closely
with the University of Zilina, to drive innovation and development of
next-generation networks in the region and beyond.

The Slovak Republic has seen
rapid growth of the relatively small telecoms industry in recent years
and is set to position the country at the forefront of
telecommunications development as they offer new services to home and
business subscribers. In conjunction with the Faculty of Electrical
Engineering, the Faculty of Management Science and Informatics and the
Faculty and Operation of Transport and communication at the University
of Zilina, the INGN facilitates a cohesive approach to the development
of the regions telecommunications infrastructure.

"We wanted to gain access to
Sonus IP-based infrastructure technology as it supports the some of the
worlds largest carrier networks, in the most sophisticated and
demanding markets. The technology is proven as one of the best in class
and these are the standards we want to develop and implement for our
region, said Professor Milan Dado, chairman of INGN. For the region
to gain a competitive edge in a connected and expanding European
market, we rely on donations to facilitate our research and
development. This donation from Sonus Networks to the Institute
demonstrates their commitment to the growth and development of our
industry."

"We are pleased with the
recent addition of Sonus platform to INGN's laboratories. This supports
our aim to develop INGN's lab into leading multi-vendor IP and NGN test
environment within Central and Eastern Europe", commented Peter Helexa,
director of strategy and new business development, and member of the
supervisory board of INGN.

For the next-generation
network research project, Sonus provided multiple solutions including
the GSX 4000 Gateway and Network Border Switch. Sonus also provided the
Sonus Insight Element Management System to provide a comprehensive
graphical user interface to manage all of the components of the Sonus
packet telephony solution.

"Sonus Networks is pleased to
offer the INGN the support it needs in its drive to further the
research and development of next-generation networks. Sonus is
committed to supporting the development of new and emerging
technologies in the region and looks forward to working closely with
the Institute to champion innovation," said Tony Morrish, vice
president, EMEA at Sonus Networks.

About Sonus Networks

Sonus Networks, Inc. is a
market leader in IP communications infrastructure 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 Westford, 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 Item 1A "Risk
Factors" of Sonus' Quarterly Report on Form 10-Q for the period ended
March 31, 2008, filed with the SEC, which identifies 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 and
uncertainties associated with the Company's restatement of its
historical stock option granting practices and accounting including
regulatory actions or litigation; risks associated with our
international expansion and growth; consolidation in the
telecommunications industry; and potential costs resulting from pending
securities and patent 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, except as required by law.

Sonus is a registered trademark of Sonus Networks, Inc. All other
company and product names may be trademarks of the respective companies
with which they are associated.