[asterisk-bugs] [JIRA] (ASTERISK-21899) Q850 Reason not forwarded between call legs

[Daren Pereira (JIRA)]

Daren Pereira created ASTERISK-21899:
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             Summary: Q850 Reason not forwarded between call legs
                 Key: ASTERISK-21899
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-21899
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
          Components: Channels/chan_sip/General
    Affects Versions: 1.8.22.0
         Environment: debian squeeze / linux
            Reporter: Daren Pereira
            Severity: Minor


We all know that SIP is not as precise as ISUP with reason of the call failure.
For example, there are no differences between
UNALLOCATED 1
NO_ROUTE_DESTINATION 3
They are all treated as "404 Not Found", that might be a big problem when running with a gateway connected to SS7 and for the one you need precise "Release Cause".
We normally can use Q850 with "use_q850_reason" in sip.conf but i discovered a problem in the forwarding of the Q850 value.
The value is simply dropped and replaced by the "not enough precise" HANGUPCAUSE

See the attached SIP/DIALPLAN debug. You'll see the :

Using Reason header for cause code: 3
and on the other leg
Reason: Q.850;cause=1

The problem is, except if i missed it in all researchs i've made, there is no way to recover the Q850 value in a DIALPLAN variables.
There is the "storesipcause" but it stores the "SIP 404 Not Found" message, not the causecode.

So this ticket is in a way an issue, in a way a improvement to make.

To bypass the problem, i made a dirty patch to chan_sip.c

Instead of doing a MASTER_CHANNEL(HASH(SIP_CAUSE,[chan_name])) when "storesipcause" is set, I define a Q850 variable containing the code.

Thank you for your comments.

Regards

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