[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=250293#comment-250293 ] 

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

I can offer some context here that might be relevant.

The reason I was adding a Proceeding() in my dialplan in the first place, was that the code at https://github.com/asterisk/asterisk/blob/master/res/res_pjsip_refer.c#L141 can cause out-of-order NOTIFYs. If a 100 Trying hasn't been sent already, it will send one _right_ before sending the 200 OK. The 100 and 200 are then so close together that they would often arrive out-of-order at the client, causing various issues.

Adding the Proceeding() in the dialplan means the 100 Trying is sent at the time of calling Proceeding(), which means there's plenty of time between that and Asterisk sending the 200 OK. But after doing that, I ran into ASTERISK-28766.

I suspect that the issue here already existed before, but was hidden by the bug in ASTERISK-28766. I'll take a deeper look when I have more time later this week.

> 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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