UE Capabilities

RFC2533 includes a framework that defines feature sets. Feature sets make up a group of media capabilities supported by a UA, individually referred to as media feature tags. In session networks, feature tag information is converted to a form specified in RFC3840 and exchanged between devices in the network to establish lists of UA capabilities. Based on these capabilities, session operation procedures are performed that facilitate preferred communications modalities.

RFC3840 defines:

• The format a UA uses to specify feature sets
• How a UA registers capabilities within the network
• An extension to the contact header so that it can include feature parameters
• The media tags that specify each capability

The full list of applicable media tags is presented in RFC 3840. Examples of tags include audio, automata, data, mobility, application and video.