[SR-Users] Upstream ignores reply, because To-tag doesn't match?

[Alex Balashov]

Hi,

To-tags are only significant at the dialog layer. Replies are matched to
a transaction by Via `branch` parameter and CSeq. See RFC 3261 § 17.1.3
for details.

Consequently, the 503 response should be matched to the initial INVITE
transaction on that basis alone.

-- Alex

On Sun, Apr 07, 2019 at 09:40:10AM -0400, Sergiu Pojoga wrote:

> To simplify, the problem seems to come down to the following: how do you
> cancel/end an early state dialog between the caller and callee after
> `fr_inv_timeout` occurs? Kam self-generates a proper CANCEL towards the
> callee, while the caller gets a `408 Request Timeout' with a different
> To-tag.
> 
> I've tried:
> dlg_bye("all") - throws an error, non-confirmed dialogs can't be terminated
> with this function
> t_cancel_callid("$dlg(callid)", "$dlg(from_cseq)", "22", "200") - doesn't
> seem to produce any action
> 
> Suggestions?
> 
> On Sat, Apr 6, 2019 at 11:25 AM Sergiu Pojoga <pojogas at gmail.com> wrote:
> 
> > Hi ppl,
> >
> > Scenario: invite from upstream is t_relayed to a client gateway. After
> > `fr_inv_timeout` occurs, in a failure route I simply t_reply with "503 -
> > Service unavailable", then exit().
> >
> > However, the upstream provider simply ignores this reply, call doesn't
> > hang up. This doesn't happen when the client's gateway generates identical
> > 503 or other negative replies.
> >
> > I suspect this is happening because the To-tag in the Kam generated 503
> > reply doesn't match with the To-tag that previously was forwarded from the
> > client's gateway to the upstream provider in the `180 Ringing`.
> >
> > Any suggestions what can be done about it?
> >
> >
> > 2019/04/06 10:42:46.127177 65.39.xxx.xxx:5060 -> 208.72.xxx.xxx:5060
> >
> >
> > SIP/2.0 180 Ringing
> >
> >
> >
> > Via: SIP/2.0/UDP
> > 208.72.xxx.xxx:5060;received=208.72.xxx.xxx;rport=5060;branch=z9hG4bK1982422573
> >
> >
> > Record-Route: <sip:65.39.xxx.xxx;lr=on;did=915.8af1>
> >
> >
> >
> > From: "SERGIU" <sip:514XXXXXXX at 208.72.xxx.xxx>;isup-oli=00;tag=1975755942
> >
> >
> > To: <sip:514XXXXXXX at 65.39.xxx.xxx>;tag=as2ab54180
> >
> >
> >
> > Call-ID: DID-28270826 at 208.72.xxx.xx
> >
> >
> >
> > CSeq: 477023 INVITE
> >
> >
> >
> > Supported: replaces, timer, path
> >
> >
> >
> > Contact: <sip:1514XXXXXXX at 65.39.xxx.xxx:5060>
> >
> >
> >
> > Content-Length: 0
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > 2019/04/06 10:42:51.072516 65.39.xxx.xxx:5060 -> 208.72.xxx.xxx:5060
> >
> >
> > SIP/2.0 503 Service Unavailable
> >
> >
> >
> > Call-ID: DID-28270826 at 208.72.xxx.xx
> >
> >
> >
> > Via: SIP/2.0/UDP
> > 208.72.xxx.xxx:5060;rport=5060;branch=z9hG4bK1982422573;received=208.72.xxx.xxx
> >
> >
> > From: "SERGIU" <sip:514XXXXXXX at 208.72.xxx.xxx>;isup-oli=00;tag=1975755942
> >
> >
> > To: <sip:514XXXXXXX at 65.39.xxx.xxx>;tag=
> > a6a1c5f60faecf035a1ae5b6e96e979a-8e82
> >
> >
> > CSeq: 477023 INVITE
> >
> >
> >
> > Server: KAM
> >
> >
> >
> > Content-Length: 0
> >
> > Thanks,
> > --Sergiu
> >

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-- 
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/