[asterisk-dev] Passing AOC information across channels

[Steven Critchfield]

On Mon, 2006-01-30 at 21:50 +0000, tim panton wrote:
> (note, lots of useful discussion removed - if you are just joining us,
> please 
> read the thread to this point).
> On 30 Jan 2006, at 18:42, Olle E Johansson wrote:

> > I don't think AST_CONTROL frames is the way to go. We must be able
> > to handle this in a more generic way, like I proposed earlier, with
> > either dialplan variables
> > or a dialplan function. Transmission of cost between call legs seems
> > to me like something you want to be in control of in the dial plan.
> > (Your service provider's cost should not be transmitted to your
> > customers).
> 
> 
> But sometimes it should be passed through asterisk. Like when you put
> an asterisk between an existing PBX
> and the PRI the pbx was connected to. If that PBX does stuff with the
> AOC (like charging cost centers or
> limiting call costs) then Asterisk needs to pass it through.

I would suggest that it doesn't transit directly through. If asterisk
could create these messages as well as consume them, then you could
write something that then could relay them. This way you get both pure
transit and a modified cost transit at with pretty much the same code. 

> In at least one of the modes the AOC value is time dependent,  you
> keep getting new (higher !) values
> through the life of the call, so just setting a single variable is not
> enough, you want to know when it was last set too.
> 
> > 
> > 
> > But I do understand why he wants it in AST_CONTROL frames on the
> > other hand, so it's not an easy fix. Anyone with a suggestion?
> 
> 
> It isn't CONTROL, but it probably should be in a  frame. It strikes me
> as being more like the HTML or TEXT frames
> in IAX. It would be nice to try and piggy back it on a voice frame,
> but that might get ugly.

It seems to me that this should be a channel variable, but I haven't
looked into how channel variables are sent from one side to the other.
Might be interesting to make sure channel variables could be transmitted
at configurable intervals during a call. Of course that would handle
IAX, but I don't know about SIP or if that is even a good option for Zap
or libpri. 

Anyone familiar with the messages passed in the D channel of ISDN want
to chime in on the thought of exposing some of the messages via channel
variables? While most calls might not benefit from it, I could see some
custom apps that might make use of the extra info.  
-- 
Steven Critchfield <critch at basesys.com>