Make sure the maxptime attribute is added to the correct offers.

........

Merged revisions 405877 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@405878 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -13472,7 +13472,7 @@ static enum sip_result add_sdp(struct sip_request *resp, struct sip_pvt *p, int
 		}
 		if (max_audio_packet_size) {
-			ast_str_append(&a_text, 0, "a=maxptime:%d\r\n", max_audio_packet_size);
+			ast_str_append(&a_audio, 0, "a=maxptime:%d\r\n", max_audio_packet_size);
 		}
 		if (!doing_directmedia) {