Re: [SR-Users] ACK Relay Issue Transaction Not Found

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(a)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(a)yahoo.com wrote: -- Alex Balashov | Principal | Evariste Systems LLC Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free) Web: http://www.evaristesys.com/, http://www.csrpswitch.com/ _______________________________________________ Kamailio (SER) - Users Mailing List sr-users(a)lists.kamailio.org https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users