Thanks for your reply. I can't see the ACK being relayed to MSTeams in network capture through in Relay Route if(is_method("ACK|BYE")) { sip_trace(); setflag(22); } but call has been established successfully. is ACK is being relayed hiddenly by Kamailio ? On Tuesday, November 24, 2020, 09:35:32 PM GMT+5, Alex Balashov abalashov@evaristesys.com wrote:
Hi,
If you take a look at the documentation for t_check_trans(), you'll see that it behaves in very different ways depending on the type of message it is handling, and is supposed to return a negative/false value in some scenarios or abort script execution -- context is very important:
https://kamailio.org/docs/modules/stable/modules/tm.html#tm.f.t_check_trans
There are two types of ACKs - hop-by-hop ACKs, which acknowledge negative final replies, and end-to-end ACKs, which are for successful final 2xx replies and meant to be relayed by Kamailio end-to-end, in the manner of a normal in-dialog request.
An ACK of this nature is a separate request and a separate transaction, though its CSeq is identical to that of the INVITE transaction it is meant to acknowledge. However, a 2xx final reply will close an INVITE transaction, subject to `max_inv_lifetime` and `wt_timer`[1] and all that stuff:
The documentation speaks to this point:
"For end-to-end ACKs (ACKs to 2xx responses for forwarded INVITE transactions) it will return true if the corresponding INVITE transaction is found and still active and false if not.
Note that the e2e ACK matching is more of a hint then a certainty. A delayed e2e ACK might arrive after the transaction wait time elapses, when the INVITE transaction no longer exists and thus would not match anything. There are also cases when tm would not keep all the information needed for e2e ACK matching (since this is not needed for a stateful proxy and it requires additional memory, tm will not keep this information unless needed by some other module or callbacks)."
So, in other words, you should not expect t_check_trans() to return true for an end-to-end ACK. It is reasonable to expect that in the vast majority of cases, it will return false. The ACK should be relayed in the same manner as any other loose-routed in-dialog request, e.g. a reinvite or a BYE. If you follow the logic of the stock configuration that Kamailio ships with, this will happen correctly by default.
-- Alex
[1] https://kamailio.org/docs/modules/stable/modules/tm.html#tm.p.wt_timer
On 11/24/20 3:24 AM, me.projects@yahoo.com wrote:
Hi When ACK is received on Kamailio from PBX t_check_trans() fails. 200 OK sent PBX from Teams and ACK from PBX is provided here.
What could be the issue.
SIP/2.0 200 OK FROM: "Ext1"sip:1102@PBX_IP;tag=e08f0a03-1120-4e13-b0e2-90d1a027c05f TO: sip:1101@KAM_IP;tag=e667397cb47c457a860222931e320b41 CSEQ: 25772 INVITE CALL-ID: a6685754-b402-4a15-82b2-5fb2551e5b58 VIA: SIP/2.0/UDP PBX_IP:7790;received=PBX_IP;branch=z9hG4bKPj170912fc-0908-40bb-8248-9f6cb560332d;rport=7790
RECORD-ROUTE: sip:sip-du-a-us.pstnhub.microsoft.com:5061;transport=tls;lr,sip:sbc.callsprout.com;transport=tls;ftag=e08f0a03-1120-4e13-b0e2-90d1a027c05f;lr,sip:KAM_IP:7790;transport=udp;ftag=e08f0a03-1120-4e13-b0e2-90d1a027c05f;lr
CONTENT-LENGTH: 353 SUPPORTED: timer CONTENT-TYPE: application/sdp ALLOW: INVITE,ACK,OPTIONS,CANCEL,BYE,NOTIFY REQUIRE: timer SESSION-EXPIRES: 1800;refresher=uac SERVER: Microsoft.PSTNHub.SIPProxy v.2020.11.16.5 i.USEA.5 X-Siptrace-Fromip: tls:KAM_IP:7790 X-Siptrace-Toip: udp:PBX_IP:7790 X-Siptrace-Time: 1606205334 607029 X-Siptrace-Method: INVITE X-Siptrace-Dir: out
ACK sip:api-du-b-usea.pstnhub.microsoft.com:443;x-i=c825abba-7203-442c-8461-994522d14365;x-c=25f3c2ce3a635971b809dc3be872e51b/s/1/63c9eea743284db99366cabf5f7dcbf5;alias=.114.132.46~5061~3 SIP/2.0 Via: SIP/2.0/UDP PBX_IP:7790;rport;branch=z9hG4bKPjaa30c14c-c965-473d-bc49-9f223f9f634c From: "Ext1" sip:1102@PBX_IP;tag=e08f0a03-1120-4e13-b0e2-90d1a027c05f To: sip:1101@KAM_IP;tag=e667397cb47c457a860222931e320b41 Call-ID: a6685754-b402-4a15-82b2-5fb2551e5b58 CSeq: 25772 ACK Route: sip:KAM_IP:7790;lr;ftag=e08f0a03-1120-4e13-b0e2-90d1a027c05f Route: sip:sbc.callsprout.com;transport=tls;lr;ftag=e08f0a03-1120-4e13-b0e2-90d1a027c05f
Route: sip:sip-du-a-us.pstnhub.microsoft.com:5061;transport=tls;lr Max-Forwards: 70 User-Agent: Asterisk Content-Length: 0 X-Siptrace-Fromip: udp:PBX_IP:7790 X-Siptrace-Toip: udp:KAM_IP:7790 X-Siptrace-Time: 1606205334 615495 X-Siptrace-Method: ACK X-Siptrace-Dir: in
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