[asterisk-dev] Passing out-of-band data in PRI call setup?

[Matthew Fredrickson]

Tony Mountifield wrote:
> In article <47CEC327.1060800 at digium.com>,
> Kevin P. Fleming <kpfleming at digium.com> wrote:
>> Tony Mountifield wrote:
>>
>>> *** Why is SUPPORT_USERUSER not defined by default?
>>> If USERUSERINFO is not set, then the User-User IE is not sent anyway,
>>> so surely having it on by default doesn't hurt anything.
>> For safety's sake, mostly. It is possible that it could be received on
>> an incoming call (without your knowledge) and then passed back out an
>> outgoing call (again without your knowledge). If you aren't prepared to
>> deal with that, it's safer for it to be off.
> 
> I don't think that could happen by accident, at least not if the call is
> passed on via the dialplan.
> 
> The incoming channel would have USERUSERINFO set, but that would not be
> inherited by the outbound channel unless the Dial was preceded by
> Set(_USERUSERINFO=${USERUSERINFO})
> 
> Is there another way a call could be passed on through Asterisk?
> 
> The reason for the mild gripe was that the boxes I wanted to try this on
> are constantly in use, with one of them never dropping to less than 8
> channels live out of 120. Because I will need to recompile chan_zap with
> SUPPORT_USERUSER defined, I will have to have a brief outage instead of
> just a dialplan reload.

There was a bug in the USER-USER code, where unintended USER-USER IEs 
were sent.  I believe the bug was subsequently fixed, but I haven't had 
a good way to test it in a while.

-- 
Matthew Fredrickson
Software/Firmware Engineer
Digium, Inc.