Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 311732)
+++ channels/chan_sip.c	(working copy)
@@ -13042,9 +13042,11 @@
 		/*! \todo We need to save the TRANSPORT here too */
 		pvt->sa = pvt->recv;
 		return 0;
+	} else if (!ast_strlen_zero(pvt->fullcontact)) {
+		return __set_address_from_contact(pvt->fullcontact, &pvt->sa, pvt->socket.type == SIP_TRANSPORT_TLS ? 1 : 0);
 	}
-
-	return __set_address_from_contact(pvt->fullcontact, &pvt->sa, pvt->socket.type == SIP_TRANSPORT_TLS ? 1 : 0);
+	/* No fullcontact so no new contact address */
+	return -1;
 }
 
 /*! \brief Parse contact header and save registration (peer registration) */
@@ -19090,7 +19092,8 @@
 			if (!reinvite)
 				build_route(p, req, 1);
 
-			if(set_address_from_contact(p)) {
+			/* If a response contains no contact, but we already have a valid host/port, don't bail */
+			if(set_address_from_contact(p) && ast_sockaddr_port(&p->sa) == 0) {
 				/* Bad contact - we don't know how to reach this device */
 				/* We need to ACK, but then send a bye */
 				if (!p->route && !req->ignore)