> My question is related to the use case when the caller hangs > up (cancels the INVITE) before INFO is received: > Sent: INVITE > Received: 183 (INVITE) > Sent: CANCEL > Received: 200 (CANCEL) > Received: INFO (with the same tags as in 183) My > softphone responds to this INFO with the 481 response code > because it considers that the early dialog and the call were > destroyed when the remote servers answered to my CANCEL with 200. > But my users are complaining to this behavior. They want to > receive 200 OK response to the INFO request. > What do you think, is this correct? MAY my softphone respond > to the INFO with 200 response when the initial INVITE was > cancelled, or it MUST respond to the INFO with 481 response > because the early dialog was terminated after successful > cancellation?
In my opinion, the answer mainly depends upon what your phone does when it receives an INVITE 200 response instead of INVITE 487. If your phone actually would prompts the user to continue the call, returning an INFO 200 response is acceptable if willing to act upon the INFO. (However I wouldn't recommend such behavior unless clearly able to indicate to caller that this is still an outgoing call instead of an incoming call.) If your phone sends an ACK and BYE instead of prompting the user, returning an INFO 481 is better even though some SIP purists might complain that the 481 should not be sent prior to receiving an INVITE 487 response. The main reason returning a 481 is typically better is because the 487 might not be received or received in a timely manner. _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
