There are very few client requirements for Communicator Web Access (2007 R2 release). All you need a supported operating system and Web browser. There is one exception: Windows users who want to share their desktop with other uses need to install the Communicator Web Access Plug-in. Communicator Web Access is currently supported on the following operating systems and Web browsers:

Microsoft Windows 2000 Service Pack 4 (SP4)

Microsoft Windows XP Service Pack 2 (SP2)

Microsoft Windows Vista

Macintosh OS 10.3.9

Macintosh OS 10.5.4

Red Hat Linux 2.16

It is possible that Communicator Web Access will run under other Web browsers or on other operating systems. However, these alternate configurations have not been tested and are not officially supported.