Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 319526)
+++ channels/chan_sip.c	(working copy)
@@ -26740,7 +26740,7 @@
 		sip_cfg.allowsubscribe = TRUE;	/* No global ban any more */
 	}
 	/* If read-only RT backend, then refresh from local DB cache */
-	if (peer->host_dynamic && !sip_cfg.peer_rtupdate) {
+	if (peer->host_dynamic && (!peer->is_realtime || !sip_cfg.peer_rtupdate)) {
 		reg_source_db(peer);
 	}