[asterisk-users] CEL custom variable in outbound channel

[Matthew Jordan]

On Thu, Jul 18, 2013 at 10:16 AM, Hristo Trendev <dist.lists at gmail.com>wrote:

> Hi,
>
> I am using Asterisk 1.8 and trying to pack some custom data in a CEL
> HANGUP event.
>
> In a master (inbound) channel I can set the CHANENL(userfield) to pass
> custom information to a CEL event. In the outbound channel created by
> Dial() I can also possibly use a macro/gosub on answer and set the
> CHANENL(userfield) from there.
>
> The problem is how to set it in an outbound channel created by Queue() for
> example or even one created by Dial(), but which was cancelled or rejected?
>
> If I read the docs correctly CEL uses a predefined set of values, which
> mostly come from the CHANNEL function, but it cannot just pull the value of
> any channel variable/function and put it in the event. Also I don't think
> that there is any such thing as function value inheritance (setting
> __CHANNEL(userfiled) so it is inherited so to say).
>
> I didn't test it myself, but there is a configuration option in
> manager.conf that allows a list of variables to be defined and they will
> then be automatically included in AMI events.
>
> Is there something similar for CEL events (with sqlite backend if that
> matters)? Can I just get any channel variable value in a CEL event? I tried
> changing the default cel_sqlite3 template to include a channel variable,
> but it is always empty.
>
>
So, this is only so helpful, as this solution only applies to Asterisk 11.
There may be another way to accomplish this in Asterisk 1.8, but this is
the first one that came to my mind - maybe someone else will have another
suggestion. If migrating to Asterisk 11 is an option for you, than maybe
this will help.

In Asterisk 11, you could use a pre-dial handler [1] to apply the userfield
directly to the outbound channel on the initial Dial. Because pre-dial
handlers are run immediately after channel creation but before dialing or
any other action is taken, they work in situations where the dial operation
fails or is cancelled. You would have something that looks something like
this:

exten => s,1,Dial(SIP/foo,,b(default^callee_handler^1))
...

exten => callee_handler,1,NoOp()
same => n,Set(CHANNEL(userfield)=my_custom_data)
same => n,Return()

Note that pre-dial handlers are not directly available in the Queue
application. However, if you use Local channel agents, then you could use
pre-dial to put the userfield information on the callee SIP channel when
the Local channel performs a Dial to the actual SIP device.

[1] https://wiki.asterisk.org/wiki/display/AST/Pre-Dial+Handlers

Matt

-- 
Matthew Jordan
Digium, Inc. | Engineering Manager
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: http://digium.com & http://asterisk.org
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