Which SIP response is considered a final response?
200 OK Indicates the request was successful.
Whether other options state the request is still in progress or request is initiated.
In SIP (Session Initiation Protocol), there are different types of responses that a user agent server (UAS) can send back to a user agent client (UAC) depending on the progress of the call setup process.
Out of the options provided, the SIP response that is considered a final response is the "200 OK" response (option C). This response indicates that the call has been successfully established and the session is in progress. Once the UAC receives a "200 OK" response from the UAS, it can start sending and receiving media packets with the other party.
The other responses mentioned in the options are provisional responses. Provisional responses are intermediate responses that indicate call progress but do not indicate the final outcome of the call setup process. The provisional responses are:
"100 Trying" (option E): This response indicates that the UAS has received the initial request and is trying to locate the user or device being called.
"180 Ringing" (option D): This response indicates that the called party's device is ringing.
"183 Session in Progress" (option A): This response indicates that the UAS has received the request, and a session is being established. However, media negotiation is still ongoing.
"199 Early Dialog Terminated" (option B): This response indicates that the UAS has terminated the early dialog. This response is not used to terminate the call, but instead to signal to the UAC that the early dialog has been terminated before a final response is received.
In summary, the "200 OK" SIP response is the final response that indicates that the call has been successfully established, while the other responses are provisional responses that indicate call progress but do not indicate the final outcome of the call setup process.