Change 183 Ringing in sipfrag body to 180 ringing. 183 Ringing isn't even a thing.

183 is actually a session progress message.

(closes issue ASTERISK-18925)
Reported by: Sebastian Denz
Tested by: jrose
Patches:
	asterisk18-use_180_instead_of_183_in_sipfrag.diff by Sebastian Denz (License #6139)
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Merged revisions 346697 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 346698 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@346699 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -23994,7 +23994,7 @@ static int handle_request_refer(struct sip_pvt *p, struct sip_request *req, int
 	/* FAKE ringing if not attended transfer */
 	if (!p->refer->attendedtransfer) {
-		transmit_notify_with_sipfrag(p, seqno, "183 Ringing", FALSE);
+		transmit_notify_with_sipfrag(p, seqno, "180 Ringing", FALSE);
 	}
 	/* For blind transfer, this will lead to a new call */