res_pjsip_session: Don't aggressively terminate on failed re-INVITE.

Per the RFC when an outgoing re-INVITE is done we should
only terminate the dialog if a 481 or 408 is received.

ASTERISK-29033

Change-Id: I6c3ff513aa41005d02de0396ba820083e9b18503

res/res_pjsip_session.c

@@ -2887,8 +2887,11 @@ static void session_inv_on_tsx_state_changed(pjsip_inv_session *inv, pjsip_trans
 							ast_sip_session_send_request_with_cb(session, tdata, cb);
 							return;
 						}
-						if (tsx->status_code != 488) {
-							/* Other reinvite failures (except 488) result in destroying the session. */
+						/* Per RFC3261 14.1 a response to a re-INVITE should only terminate
+						 * the dialog if a 481 or 408 occurs. All other responses should leave
+						 * the dialog untouched.
+						 */
+						if (tsx->status_code == 481 || tsx->status_code == 408) {
 							if (pjsip_inv_end_session(inv, 500, NULL, &tdata) == PJ_SUCCESS
 								&& tdata) {
 								ast_sip_session_send_request(session, tdata);