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

[Carlos Mendioroz (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-28828?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=250372#comment-250372 ] 

Carlos Mendioroz commented on ASTERISK-28828:
---------------------------------------------

This is above my level of understanding. 
But it seems to me that the reordering of messages is in fact a trigger of the issue. I do have a trace where an inverted sequence did not upset Teams, but the order of the responses is the canonical one (Trying, Ringing) so my take is that somehow they made it to the link in the right order.
So given that there is some kind of queuing and message generation order is not always kept, I decided to revert the patch that causes the delayed Trying (Asterisk-25771, change id I09cfc9a5d6ed4c007bc70625e0972b470393bf16) and that seems to fix things.
Correct fix, I guess, would be to somehow enforce TX order, but that is inside PJSIP library ?

> 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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