I'll take a look at the source code or the other way as discussed in previous mailing-list thread is using ESL to capture the parking event and do as required.
I can't imagine to access a variable after I park the call, could there be anything like execute_on_answer, or api_on_bridge..something like execute_on_park so that whenever a call is parked user has the control to perform some lua code or anyother XML dialplan where the event variables are accessible to be played with?
Its been long time but now I'm recalling that for distributed parking lots among multiple Asterisk servers I had to share a common memcache table where I manually loop from starting parking extension and using a parking slot which is not already saved there.
Please share your thoughts.
Thanks,
Sammy