CM does not send back ACK to UAS when calling SIP

Doc ID		SOLN275833
Version:		1.0
Status:		Published
Published date:		28 Sep 2015

Author:

Andras Varga

Details

CM won't send an ACK back to UAS when CM calling SIP

CM: R016x.03.0.124.0

Call flow: H.323 IP Phone calls out via SIP trunk and via SBC.

List trace findings:

15:13:41.183 |--INVITE-->| (93) T:+called party F:+<caller party> U:+<called party>

15:13:41.190 |<--Trying--| (93) 100 Trying

15:13:42.010 |<--Ringing-| (93) 180 Ringing

15:13:49.018 |<--200 OK--| (93) 200 OK

15:13:49.510 |<--200 OK--| (93) 200 OK

15:13:50.515 |<--200 OK--| (93) 200 OK

15:13:52.522 |<--200 OK--| (93) 200 OK

15:13:56.525 |<--200 OK--| (93) 200 OK

15:14:00.530 |<--200 OK--| (93) 200 OK

15:14:02.836 |<----BYE---| (93) sip:<caller Party>@<IP address>

15:14:02.837 |--Call Do->| (93) 481 Call Does Not Exist (no local tag match)

15:16:41.188 |--CANCEL-->| (93) sip:<called party>@<IP address>

15:16:41.193 |<--Call/Tr-| (93) 481 Call/Transaction Does Not Exist

Debug & MST trace findings:

CM does not send ACK because the 180 ringing and the 200 OK messages have parser error. The debugs point to
# 20150923 151342010 12787547 capro 885 MED cUASIPStack decodeMessage
# 20150923 151342010 12787548 capro 885 MED allow Parse failed early Expected CR/LF to terminate header

Problem Clarification

CM does not send back ACK to UAS when calling SIP. The number is working, managed to call from cellphone. ACME SBC sends 200 OK.

Cause

One of the content of the ALLOW header was invalid.
Wrong ALLOW:

INVITE,ACK,OPTIONS,BYE,CANCEL,REGISTER,REFER,SUBSCRIBER,NOTIFY,MESSAGE,INFO,PRACK,UPDATE

Fixed ALLOW:

INVITE,ACK,OPTIONS,BYE,CANCEL,REGISTER,REFER,SUBSCRIBE,NOTIFY,MESSAGE,INFO,PRACK,UPDATE

Solution

The fix the wrong ALLOW header.

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