SIP Response Codes
List of SIP response codes The Session Initiation Protocol (SIP) is a signalling protocol used for controlling communication sessions such as Voice over IP telephone calls. SIP is based around request/response transactions, in a similar manner to the Hypertext Transfer Protocol (HTTP). Each transaction consists of a SIP request (which will be one of several request methods), and at least one response. Contents 11xx—Provisional Responses 22xx—Successful Responses 33xx—Redirection Responses 44xx—Client Failure Responses 55xx—Server Failure Responses 66xx—Global Failure Responses 1xx—Provisional Responses 100 Trying Extended search being performed may take a significant time so a forking proxy must send a 100 Trying response. 180 Ringing Destination user agent received INVITE, and is alerting user of call. 181 Call is Being Forwarded Servers can optionally send this response to indicate a call is being forwarded. 182 Queued Indicates that the destination was temporarily unavai...