--- channels/chan_sip.c	(revisión: 184564)
+++ channels/chan_sip.c	(revisión: 184565)
@@ -2947,7 +2947,9 @@
 		ASTOBJ_UNREF(p, sip_destroy_peer);
 		return res;
 	}
-	
+
+	do_setnat(dialog, ast_test_flag(&dialog->flags[0], SIP_NAT) & SIP_NAT_ROUTE);
+
 	ast_string_field_set(dialog, tohost, peer);
 
 	if (sin) {
