Abstract
RFC 3261 defines SIP, the Session Initiation Protocol for initiating, modifying, and terminating multimedia sessions such as VoIP calls and video conferences. It specifies the request methods (INVITE, ACK, BYE, CANCEL, OPTIONS, REGISTER), all response codes, and the SDP negotiation model.
Defined Status Codes
SIP 100 Trying
SIP 180 Ringing
SIP 200 OK
SIP 301 Moved Permanently
SIP 400 Bad Request
SIP 401 Unauthorized
SIP 403 Forbidden
SIP 404 Not Found
SIP 408 Request Timeout
SIP 480 Temporarily Unavailable
SIP 486 Busy Here
SIP 487 Request Terminated
SIP 500 Server Internal Error
SIP 503 Service Unavailable