Hiddenly? :-)

-- Alex

On 11/24/20 12:22 PM, me.projects@yahoo.com wrote:

> 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
> <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
> <https://kamailio.org/docs/modules/stable/modules/tm.html#tm.p.wt_timer>
>
> On 11/24/20 3:24 AM, me.projects@yahoo.com
> <mailto: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
> <mailto:1102@PBX_IP>>;tag=e08f0a03-1120-4e13-b0e2-90d1a027c05f
>  > TO: <sip:1101@KAM_IP
> <mailto: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>
>
>  >
>  > CONTACT:
>  >
> <sip:api-du-b-usea.pstnhub.microsoft.com:443;x-i=c825abba-7203-442c-8461-994522d14365;x-c=25f3c2ce3a635971b809dc3be872e51b/s/1/63c9eea743284db99366cabf5f7dcbf5;ias=52.114.132.46~5061~3>
>
>  >
>  > 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
> <mailto:1102@PBX_IP>>;tag=e08f0a03-1120-4e13-b0e2-90d1a027c05f
>  > To: <sip:1101@KAM_IP
> <mailto: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
>
>  >
>  > _______________________________________________
>  > Kamailio (SER) - Users Mailing List
>  > sr-users@lists.kamailio.org <mailto:sr-users@lists.kamailio.org>
>  > https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
> <https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users>
>  >
>
> --
> Alex Balashov | Principal | Evariste Systems LLC
>
> Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
> Web: http://www.evaristesys.com/, <http://www.evaristesys.com/,
>  >http://www.csrpswitch.com/ <http://www.csrpswitch.com/>
>
> _______________________________________________
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