--- channels/chan_sip.c.orig	2016-07-01 06:42:01.830651938 -0400
+++ channels/chan_sip.c	2016-07-01 10:13:48.479650585 -0400
@@ -13001,7 +13001,12 @@
 
 	ast_format_generate_sdp_fmtp(format, rtp_code, a_buf);
 
-	framing = ast_format_cap_get_format_framing(p->caps, format);
+	/* iLBC should not use cap_get because we don't care what the other end wants */
+	if (ast_format_cmp(format, ast_format_ilbc) == AST_FORMAT_CMP_EQUAL) {
+		framing = ast_format_get_default_ms(format);
+	} else {
+		framing = ast_format_cap_get_format_framing(p->caps, format);
+	}
 
 	if (ast_format_cmp(format, ast_format_g729) == AST_FORMAT_CMP_EQUAL) {
 		/* Indicate that we don't support VAD (G.729 annex B) */
@@ -13009,6 +13014,9 @@
 	} else if (ast_format_cmp(format, ast_format_g723) == AST_FORMAT_CMP_EQUAL) {
 		/* Indicate that we don't support VAD (G.723.1 annex A) */
 		ast_str_append(a_buf, 0, "a=fmtp:%d annexa=no\r\n", rtp_code);
+	} else if (ast_format_cmp(format, ast_format_ilbc) == AST_FORMAT_CMP_EQUAL) {
+		/* Add information about us using only 30 ms packetization */
+		ast_str_append(a_buf, 0, "a=fmtp:%d mode=%u\r\n", rtp_code, framing);
 	} else if (ast_format_cmp(format, ast_format_siren7) == AST_FORMAT_CMP_EQUAL) {
 		/* Indicate that we only expect 32Kbps */
 		ast_str_append(a_buf, 0, "a=fmtp:%d bitrate=32000\r\n", rtp_code);