[TriLUG] Semi-OT: Asterisk Parking setup

[Brian Henning]

Hi Gang,

I've just deployed an Asterisk-powered VOIP PBX at my company.  So far, so
good.  We have Cisco/Linksys SPA942 desk phones.

I think Asterisk's default call parking function is awful.  Blind transfer
followed by a callback from the PBX with the line number?  Way too much room
for error / failure, and involves too many button presses.

With the 942s, I can configure line buttons with BLF and speed-dial on
parking lot extensions.  What I'd love to do is combine that with a smart
dialplan to result in the following flow for parking a call:

1) First user (receptionist, perhaps) optionally places call on hold
2) User presses a free (glowing green) parking line key
3) User hangs up
4) Another user picks up the phone and presses the now occupied parking lot
line key (now red)
5) The new user talks to the parked person.

This would require Asterisk to respond to the parking lot extension as
follows, wherein lies the rub:

1) See if parking lot is occupied.  If so, pick up the parked call.
2) If not, magically figure out what channel the held call on the current
SIP extension is on
3) Bridge the current call with the held channel and park on the specified
lot
(4) If park fails (another thread beat us to the lot, e.g.), place the
inbound call back on hold and play a message/send text to the user

What I haven't been able to figure out:
 -- How can Asterisk determine the channel of a held call for a given SIP
extension?
 -- How can I specify a parking lot (override default FCFS behavior)?
 

If this can't be done by clever extensions.conf engineering, might it be
possible through a separate app?  I've never written an Asterisk app before,
but it sounds like a fun challenge...

Cheers and many thanks,
~Brian


------------------------------------------------------ 
          Brian Henning, Software Engineer

    /\    Pine Research Instrumentation 
   //\\   5908 Triangle Drive 
  ///\\\  Raleigh, NC 27617 
 ////\\\\ USA 
    || 
    ||    phone: 919.782.8320 
          fax:   919.782.8323 
          email: bhenning at pineinst.com 
------------------------------------------------------