Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 33031)
+++ channels/chan_sip.c	(working copy)
@@ -14946,7 +14946,7 @@
 		changed |= ast_rtp_get_peer(vrtp, &p->vredirip);
 	else
 		memset(&p->vredirip, 0, sizeof(p->vredirip));
-	if (p->redircodecs != codecs) {
+	if (codecs && (p->redircodecs != codecs)) {
 		p->redircodecs = codecs;
 		changed = 1;
 	}