Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 38417)
+++ channels/chan_sip.c	(working copy)
@@ -3238,8 +3238,15 @@
 					update_call_counter(p, INC_CALL_LIMIT);
 				}
 			} else {	/* Incoming call, not up */
+                                const char *cause = pbx_builtin_getvar_helper(ast,"PRI_CAUSE");
+                                int icause = ast->hangupcause ? ast->hangupcause : -1;
+                                if (cause) {
+                                        if (atoi(cause))
+                                                icause = atoi(cause);
+                                }
+
 				const char *res;
-				if (ast->hangupcause && (res = hangup_cause2sip(ast->hangupcause)))
+				if ((res = hangup_cause2sip(icause)))
 					transmit_response_reliable(p, res, &p->initreq);
 				else 
 					transmit_response_reliable(p, "603 Declined", &p->initreq);