asterisk users - Feb 2005 - How to map zap channels to ISDN extensions on queues?

I need to determine the state of extensions/port based on active 
channels on my asterisk. For SIP and AIX extensions this is not a real 
problem because the channel names they create relate to the SIP/AIX 
extensions (just strip the '-' sign and anything after). For ISDN 
extensions addressed by Zap, it turned out problematic. As I figured out 
there'se no direct relation between a Zap channel (name) and the ISDN 
extension currently occupying it.

The actual problem is this. I have a queue where I dynamically 
add/remove interfaces to/from. My queue may look something like this:

helpdesk has 0 calls .....
   Members:
      SIP/port1 (dynamic) has taken no calls yet
      ZAP/g1/100 (dynamic) has taken no calls yet
      ZAP/g1/200 (dynamic) has taken no calls yet
   No Callers

When some one is calling my queue and is being bridged to one of the 
ISDN members, I want to know which extension it got bridged to 
(zap/g1/100 or zap/g1/200). I can't seem to figure it out based on the 
Zap channel to the member extension, neighter based on the incomming 
channel. I've tried to based on several sources:
-  show channels (CLI)
-  show channel (CLI)
-  events information (Asterisk Manager API)
Neither of those appear to help me determine wich ISDN extension are in use.

I figured out that in case a call is being bridged to a queue member, 
the caller channel's CDR contains the value I want to have (e.g. 
zap/g1/100). It's stored in the lastappdata field. The problem is that 
the CDR is written after the call is being terminated. I need it 
preferabely as soon as the extension at zap/g1/100 starts ringing.

Looking at the source code of asterisk, I believe to have figured out 
that CDR data is internally being stored within any channel object. Now 
the big question is, if this data is accessable from a CLI or Asterisk 
Manager API (telnet)?

Does anybody recognize the above problem?

Is there a clean solution?

Is the real solution to the problem writing something like a zap channel 
tracker (patch)?

TIA,

Elwin

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HeuvelTop ICT Diensten v.o.f.
Elwin Andriol              tel: +31 65 08 134 91
Utrecht, Nederland         fax: +31 30 602 22 71
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