--- channels/chan_sip.c	(Asterisk 13.6.0)
+++ channels/chan_sip.c	(working copy)
@@ -13386,3 +13386,3 @@
 		/* Finally our remaining audio/video codecs */
-		for (x = 0; x < ast_format_cap_count(p->caps); x++) {
+		for (x = 0; ast_test_flag(&p->flags[0], SIP_OUTGOING) && x < ast_format_cap_count(p->caps); x++) {
 			tmp_fmt = ast_format_cap_get_format(p->caps, x);