Behavior in cancelling INVITE session when no provisional response has been received

[bennylp]

RFC 3261 Section 9.1 says that CANCEL MUST NOT be sent if the INVITE transaction has not received any provisional response. So pjsip behaves correctly by not sending CANCEL here.

On the other hand, the section also says that the dialog must wait until either a response is received, or 64*T1 elapsed. When a provisional response is received, CANCEL should be sent, and when there is no response after 64*T1, the session can be destroyed.

This is the part where pjsip is not compliant.