[asterisk-bugs] [JIRA] (ASTERISK-28811) Crash occurs when fax session switches from T.38 to audio

[Joshua C. Colp (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-28811?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=250468#comment-250468 ] 

Joshua C. Colp commented on ASTERISK-28811:
-------------------------------------------

I don't believe that issue is related, and switching to voice in that scenario isn't required and I don't believe Asterisk has ever done so. This is because when a re-INVITE Is sent the previous SDP negotiation and state is kept and only replaced if it was successful. This means that if you send a re-INVITE and it receives a 488 then things continue on, as if the re-INVITE was never attempted.

"During the session, either Alice or Bob may decide to change the
   characteristics of the media session.  This is accomplished by
   sending a re-INVITE containing a new media description.  This re-
   INVITE references the existing dialog so that the other party knows
   that it is to modify an existing session instead of establishing a
   new session.  The other party sends a 200 (OK) to accept the change.
   The requestor responds to the 200 (OK) with an ACK.  If the other
   party does not accept the change, he sends an error response such as
   488 (Not Acceptable Here), which also receives an ACK.  However, the
   failure of the re-INVITE does not cause the existing call to fail -
   the session continues using the previously negotiated
   characteristics."

The 481 would be concerning, but I don't think anything that has been done would have changed anything there.

> Crash occurs when fax session switches from T.38 to audio
> ---------------------------------------------------------
>
>                 Key: ASTERISK-28811
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-28811
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: pjproject/pjsip
>    Affects Versions: 16.9.0
>         Environment: CentOS Linux release 7.7.1908 (Core) 3.10.0-1062.4.3.el7.x86_64
>            Reporter: Alexey Vasilyev
>            Assignee: Alexey Vasilyev
>              Labels: fax, patch
>         Attachments: ASTERISK-28811-2.diff, cisco-pbx.txt, core.28811.tar.gz, crash1-backtrace.txt, crash1-sip-trace.txt, crash2-backtrace.txt, crash2-sip-trace.txt, pbx-fax.txt, pjsip.conf, sip-flow-488.txt, sip-trace-488.txt
>
>
> During sending fax from Cisco SPA112 device through several Asterisk servers, latest updated server is crashed (Asterisk 16.9.0). But we can't reproduce crash, as sometimes faxes send fine, from other Cisco SPA112 devices faxes just stopped sending (receiving works fine). After downgrade to 16.8.0 everything works fine again.



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