[asterisk-dev] 'IAX2 call variable passing between servers '

[John Todd]

At 12:48 PM -0500 7/27/06, Tilghman Lesher wrote:
>On Thursday 27 July 2006 11:55, Douglas Garstang wrote:
>>  Found this thread on this list, from almost three years ago.
>  > http://lists.digium.com/pipermail/asterisk-dev/2003-December/002398.html
>  >
>>  It talks about passing variables in IAX2.
>>
>>  Was any of it ever implemented?
>
>No, and it probably won't be, until it gets past the "wouldn't it be
>cool if..." stage.  Not to mention that debugging a session where
>the variables could change midexecution in the dialplan would be
>pure hell.
>
>--
>Tilghman

Can you explain a bit more how the variables might change 
mid-execution?  I don't quite follow this, but I perhaps had some 
assumptions that were built into my original idea that I did not make 
obvious.  Let me put a few of them out here for discussion:

  - any variables with "outbound." as a prefix would be sent with
      any Dial execution, and could not be altered once the Dial
      has been run.  In other words: variables would be transmitted
      only once to the remote server, during the call setup and could
      and should not change during the call (though that does sound
      like it could be done with both SIP and IAX2, it seems too
      complex to tackle for a first swing at such variable transport.)

   - any received variables would not change once the dialplan started
      executing on the receiving machine, so variables would not
      change once the call setup request had been accepted by the
      remote machine.  In other words, "inbound." prefixed variables
      would never change during the life of a call.

The good news is that since I wrote that original post several years 
ago, there is now the ability to parse SIP headers within the 
dialplan, so that with a little creative string manipulation it is 
possible to move variables between two systems with SIP headers.  Now 
the only thing remaining is the ability to do the same thing with 
IAX2.  This seems a bit backwards - Asterisk seems like it should 
easily move variables around in it's native protocol instead of in 
SIP, but that's the way it is until someone comes up with the code. 
Volunteers?  :-)

JT