Microsoft and RADVISION Sign Licensing Agreement to Provide Live Communications Server-Compatible SIP Toolkits; Licensing Agreement Simplifies Development of Solutions that Interoperate with Microsoft Office Live Communications Server 2005.

REDMOND, Wash. & FAIR LAWN, N.J. -- Today, Microsoft Corp. (Nasdaq: MSFT) and RADVISION (Nasdaq:RVSN), a leading provider of multimedia conferencing, communications platforms and software developer toolkits, announced a licensing agreement that will enable third-party developers to integrate the communications capabilities of Microsoft(R) Office Live Communications Server 2005 with additional SIP communications platforms.

As part of the agreement, Microsoft is licensing to RADVISION the SIP extensions for Live Communications Server. RADVISION will implement and integrate the extensions into its toolkit products and offer the extensions to third-party developers. The SIP extensions for Live Communications Server will be available as optional add-ons to the award-winning RADVISION SIP, SIP Server, and Videophone SIP toolkits. Existing RADVISION SIP customers also may license the SIP extensions as an add-on to SIP toolkits previously licensed from RADVISION.

"We are pleased that RADVISION is embracing the SIP standard to extend interoperability for our third-party developers with Live Communications Server on non-Windows(R) operating systems in addition to Windows-based operating systems," said Gurdeep Singh Pall, Corporate Vice President of Microsoft's Unified Communications Group. "The SIP extensions enable developers to unlock innovation to help businesses make better decisions more quickly by connecting people, information and business processes."

Boaz Raviv, CEO of RADVISION, added, "We are proud to extend RADVISION's portfolio of SIP-based solutions to Live Communications Server environments. We see Live Communications Server interoperability as an excellent potential for new and add-on sales, and we believe it adds strong value to our rich SIP portfolio. We are proud that Microsoft selected RADVISION as its exclusive software toolkit vendor for providing these SIP extensions to the market."

Benefits for Third-Party Developers

The SIP extensions for Live Communications Server will allow third-party developers to apply the power of software and software platforms to improve communications across networks, devices and systems. Specifically, the third-party developers will be able to:

--Integrate Live Communications Server capabilities into solutions based on IP-PBX, IP/video phones for wire line and wireless, SIP proxies, WIFI-phones, handsets and other embedded devices for Live Communications Server environments.

--Enable IP Multimedia Subsystem (IMS) compatibility, which will allow developers to implement products for the mobile environment that are simultaneously IMS and Live Communications Server compatible.

RADVISION's SIP extensions to Live Communications Server are based on the industry-standard SIP (Session Initiation Protocol) for Instant Messaging and Presence Leveraging Extensions (SIMPLE). SIP and SIMPLE provide a rich set of solutions for computer and telephone interaction. Microsoft and RADVISION support the SIP/SIMPLE effort, demonstrating both companies' strong commitment to develop standards-based communications solutions built on methodologies that can be broadly adopted and integrated.

Availability

General availability of the SIP extensions for Live Communications Server is expected in the second half of 2006. RADVISION will offer demonstrations of RADVISION SIP toolkits interoperating with Live Communications Server at the RADVISION booth at the Voice On the Network (VON) conference and exhibition in San Jose, Calif., March 15-17.

Existing and new RADVISION customers can license from RADVISION the SIP software toolkits with SIP extensions to Live Communications Server as optional add-ons to the RADVISION SIP, SIP Server, and Videophone SIP toolkits.

Live Communications Server protocol extensions for Windows-based solutions currently are available to third-party developers through Microsoft.

About Microsoft

Founded in 1975, Microsoft (Nasdaq "MSFT") is the worldwide leader in software, services and solutions that help people and businesses realize their full potential.

About RADVISION

RADVISION (Nasdaq: RVSN) is the industry's leading provider of high quality, scalable and easy-to-use products and technologies for videoconferencing, video telephony, and the development of converged voice, video and data over IP and 3G networks. For more information please visit our website at www.radvision.com.

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The names of actual companies and products mentioned herein may be the trademarks of their respective owners.

This press release contains forward-looking statements that are subject to risks and uncertainties. Factors that could cause actual results to differ materially from these forward-looking statements include, but are not limited to, general business conditions in the industry, changes in demand for products, the timing and amount or cancellation of orders and other risks detailed from time to time in RADVISION's filings with the Securities Exchange Commission, including RADVISION's Form 20-F Annual Report. These documents contain and identify other important factors that could cause actual results to differ materially from those contained in our projections or forward-looking statements. Stockholders and other readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date on which they are made. We undertake no obligation to update publicly or revise any forward-looking statement.