Microsoft recommends that Microsoft Office Communicator users use qualified communications devices, including phones, headsets, webcams and other devices that display the Optimized for Microsoft Office Communicator wordmark. This wordmark indicates that a communications device will provide a high quality user experience, with ”just works” installation, rich audio and video, and a lower total cost of ownership.
Phones and devices that do not display the wordmark have not been tested and qualified by Microsoft.
For more Information see here http://technet.microsoft.com/en-us/bb970310.aspx
Source: Microsoft
