Windows® Mobile-Based 3G PDA-Phone, with NVIDIA® Video Encoding and Graphics Chip, to be Sold by O2

Tel Aviv (July 17, 2007) –

RADVISION (Nasdaq:RVSN), a leading provider of video network infrastructure and developer tools for unified visual communications over IP, 3G, and emerging next-generation IMS networks, announced today that ARIMA Communications, a leading OEM / ODM and integrated service provider headquartered in Taiwan, has licensed and used RADVISION’s 3G-324M Toolkit and ProLab 3G-324M Testing Solution for the development of a video-enabled 3G PDA-phone. Arima is using RADVISION’s complete 3G Video Telephony Application to integrate the platform into Windows Mobile through the RADVISION Professional Services Division. The Xda Flame PDA-phone, with an NVIDIA embedded video encoding and graphics chip, is currently being marketed by O2 Asia Pacific & Middle East (“O2 AP&ME”), a leading provider of innovative, premium converged mobile devices and a member of Telefónica O2 Europe, a leading provider of mobile communications services in Europe.

“We are especially impressed with RADVISION’s intuitive technology when it comes to all aspects of video telephony, and RADVISION’s clear IMS roadmap,” said Mr. Owen Chen, President of Arima Communications. “This allowed us to focus on the Xda Flame’s rich feature set. RADVISION technology took care of all the complex signaling and multimedia capabilities.”

The Xda Flame is the latest feature product offered by O2, and is the first PDA-phone to feature two processors – an NVIDIA® GoForce® 5500 GPU and an Intel® CPU. In addition to the power to deliver a rich multimedia experience, it features also a substantial 2GB of onboard memory, TV-out functionality and a generous 3.6″ TFT VGA LCD screen.

Arima’s Xda Flame PDA-phone runs on the Windows Mobile operating system. T. It is equipped with full integration for the Windows Mobile operating system, as well as easy-to-use APIs, optimized CPU usage, patent-pending multiplexing technology, and innovative features that reduce development time and ensure excellent interoperability. Arima uses the RADVISION technology in several other 3G products currently under development.

“Arima’s choice to use our 3G developer and testing tools further validates that when it comes to interoperability and fast-time-to-market, RADVISION’s products and solutions are ideal,” said Tsahi Levent-Levi, Product Manager for RADVISION’s Technology Business Unit. “Our 3G-324M Toolkit and ProLab(TM) Testing Solutions are especially suited for handsets using Windows Mobile operating systems.”

For more information on O2 Xda Flame, please visit www.seeo2.com/flame/.

About RADVISION

RADVISION (Nasdaq: RVSN) is the industry’s leading provider of market-proven products and technologies for unified visual communications over IP, 3G and IMS networks. With its complete set of standards-based video networking infrastructure and developer toolkits for voice, video, data and wireless communications, RADVISION is driving the unified communications evolution by combining the power of video, voice, data and wireless – for high definition video conferencing systems, innovative converged mobile services, and highly scalable video-enabled desktop platforms on IP, 3G and emerging next-generation IMS networks. For more information about RADVISION, visit http://www.radvision.com/.

About Arima

Arima Communications was founded in August 1999 as a member of the Arima Group, specializing in the research, development, manufacturing and marketing of mobile communications products. Currently, its main products are multi-band GSM / GPRS, 3G mobile phones and smart phones. Arima Communications’ strategy is to integrate market research, product design, R&D, manufacturing, product certification, global logistics and after-sales service into a comprehensive solution in communication technology for customers. In 2006, Arima Communications’ consolidated revenue was approximately 24.8 billion NTD and employed around 3,500 staff. Arima Communications is headquartered in Yingge, Taipei. Operation Center is located in Jhonghe, Taipei. R&D Centers are located in four places, Jhonghe and Hsinchu in Taiwan; Nanjing and Hangzhou in China. Manufacturing Centers are located in Yingge, Taiwan and Wujiang, China.

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.

Source: RADVISION