Use H264 video codec, if exist
Custom string associated with the call session. It can be later obtained from Call History using HTTP API. Maximum size is 200 bytes.
Optional custom parameters (SIP headers) that should be passed with call (INVITE) message. Parameter names must start with "X-" to be processed by application. IMPORTANT: Headers size limit is 200 bytes.
The number to call. The international format E.164 is preferable