asterisk users - Oct 2004 - Can Asterisk provide Answer Supervision signalling to a channel b ank via T1?

I have an older Newbridge Mainstreet 3624 upon which I'm terminating some
analog DID lines. They are effectively loop-start trunks with battery
supplied by me (ie. FXO) and consumed by the serving central office. One
major part of DID is the requirement for providing Answer Supervision in the
form of battery polarity reversal on the analog trunks. Without it wierd
things start happening, like one way audio, calls torn down by the CO after
a timeout period and so on...

On my channel bank the reversal relays seem to be controlled by the state of
the A bit going across the T1 to the bank - in all other ways they're loop
start trunks. Is there a way to get Asterisk to correctly present the Answer
state in that bit? I believe what I'm looking for is FXO/DPT (Dial Pulse
Terminate). The central office half would be the FXS/DPO (Dial Pulse
Originate) side.

I've tried Koolstart, but the only time it toggles the A bit is upon
disconnect and then only for about half a second. Which seems to be an
attempt at open loop disconnect supervision.

I think what I'm looking for is a bit progression like this:

   Tx   Rx   (relative to channel bank)
  ABCD ABCD  
  0000 0101  Both ends on hook
  1100 0101  Call starting, near end still on hook 
  1100 1111  Call connected, both ends off hook
  ...
  0000 1101  Far end hangup, near end still off hook
  0000 0101  Call torn down, both ends on hook

However, if anyone has a good reference for RBS bit patterns for DPO/DPT
perhaps they could post it to the list?

Thanks.

Kris Boutilier
Information Systems Coordinator
Sunshine Coast Regional District