[asterisk-bugs] [JIRA] (ASTERISK-28828) NOTIFY sequence upsets MS Teams SIP trunk

[lvl (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-28828?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=250313#comment-250313 ] 

lvl commented on ASTERISK-28828:
--------------------------------

I checked the supplied SIP trace.

So Asterisk receives a 100 Trying and then a 180 Ringing from the transferee. That prompts it to subsequently generate a 100 Trying and a 180 Ringing NOTIFY for the transferer. However, the two notifies end up being sent out-of-sequence and thus rightfully rejected by the MS Teams server.

Indeed before the patch in ASTERISK-28766 the 100 Trying NOTIFY would set {{progress->subclass = AST_CONTROL_PROCEEDING}} which would in some scenario's prevent the SIP 180 Ringing (and the 200 OK) from generating a NOTIFY. If only one NOTIFY is generated it won't get out-of-sequence.

So reverting ASTERISK-28766 might fix this specific scenario, but will cause other issues and won't fix the underlying problems. So I think this issue should look at: how can we prevent Asterisk from sending the NOTIFYs out-of-sequence.

In the mean time, the issue can probably be alleviated the same way I did: add a Proceeding() in the dialplan before the Dial().

> NOTIFY sequence upsets MS Teams SIP trunk
> -----------------------------------------
>
>                 Key: ASTERISK-28828
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-28828
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_pjsip_refer
>    Affects Versions: 17.3.0
>         Environment: Ubuntu 18.04 install from sources
>            Reporter: Carlos Mendioroz
>            Assignee: lvl
>            Severity: Minor
>
> Resuming an on hold call from MS Teams side often results in the call going to limbo. Trace shows out of order NOTIFYs and 500 response to a Trying event.
> On Joshua's advise, rolled back https://gerrit.asterisk.org/c/asterisk/+/13852 and even though the out of order Trying subsists, it does not gerenate a 500 and the call resumes correctly.
> Discussion here:
> https://community.asterisk.org/t/sip-xfers-via-reinvite-refer-and-order-of-notifys/83572



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