This fix introduced via bug 8233

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@47176 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -5813,6 +5813,10 @@ static void add_codec_to_sdp(const struct sip_pvt *p, int codec, int sample_rate
 
 	if (fmt.cur_ms && (fmt.cur_ms < *min_packet_size))
 		*min_packet_size = fmt.cur_ms;
+
+	/* Our first codec packetization processed cannot be less than zero */
+	if ((*min_packet_size) == 0  && fmt.cur_ms)
+		*min_packet_size = fmt.cur_ms;
 }
 
 /*! \brief Get Max T.38 Transmission rate from T38 capabilities */