diff --git a/ChangeLog b/ChangeLog
index bfa067675d..f46f9907ac 100755
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2005-11-15  Kevin P. Fleming  <kpfleming@limerick.digium.com>
 
+	* channels/chan_sip.c (add_codec_to_sdp): add 'annexb=no' to G.729A SDP (issue #5539)
+
 	* channels/chan_alsa.c (alsa_hangup): handle autohangup properly (issue #5672)
 
 	* channels/chan_misdn.c (and other files): various fixes (issue #5739)
diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 2de41da8ea..9d80d00b8b 100755
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -4265,6 +4265,9 @@ static void add_codec_to_sdp(const struct sip_pvt *p, int codec, int sample_rate
 	ast_build_string(a_buf, a_size, "a=rtpmap:%d %s/%d\r\n", rtp_code,
 			 ast_rtp_lookup_mime_subtype(1, codec),
 			 sample_rate);
+	if (codec == AST_FORMAT_G729A)
+		/* Indicate that we don't support VAD (G.729 annex B) */
+		ast_build_string(a_buf, a_size, "a=fmtp:%d annexb=no", rtp_code);
 }
 
 static void add_noncodec_to_sdp(const struct sip_pvt *p, int format, int sample_rate,