The features module provides application information about the various features possibly available through the sofia-sip-ua binary API.
The sofia_sip_name_version contains the name and release of currently installed libsofia-sip-ua.so library. The macro SOFIA_SIP_NAME_VERSION contains the name and release of currently available include files.
The Sofia SIP binary API hides some protocols used under the SIP stack. While the binary API stays the same, the features are not necessarily there. These features are mainly related to encryption, compression and underlying transports.