fix codec neg

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@4276 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/endpoints/mod_sofia/mod_sofia.c

@@ -802,7 +802,9 @@ static void tech_set_codecs(private_object_t *tech_pvt)
         codec_string = abs;
     } else {
         if (!(codec_string = switch_channel_get_variable(channel, "codec_string"))) {
-            codec_string = tech_pvt->profile->codec_string;
+			if (tech_pvt->profile->codec_string) {
+				codec_string = switch_core_session_strdup(tech_pvt->session, tech_pvt->profile->codec_string);
+			}
         }
         
         if ((ocodec = switch_channel_get_variable(channel, SWITCH_ORIGINATOR_CODEC_VARIABLE))) {