[Asterisk-Users] Zap call bridge drops randomly

[mattf]

Hello,

We have a call redirection system setup inhouse to send calls from an
incoming line on a T1 to an external dialed out number:
  Zap(call comes in) -> Asterisk -> Zap(call dials out)

The call comes in on a Robbed-bit T1 (d4/ami EM Wink) and goes out on a PRI.
We are using Asterisk release 1.0.5

Randomly the calls will drop less than a minute into the call. The Debug
messages at the end of the call always say something like this: (incoming
call on 58, outgoing on 73) 

Feb 21 11:37:28 DEBUG[16804]: Exception on 63, channel 58
Feb 21 11:37:28 DEBUG[16804]: Got event On hook(1) on channel 58 (index 0)
Feb 21 11:37:28 DEBUG[16804]: disabled echo cancellation on channel 58
Feb 21 11:37:28 DEBUG[16804]: Unlinking slave 73 from 58 

The strange thing is that the person that called in did not hang up, in fact
they are usually talking when this call goes dead. Only about 10% of the
calls that redirect have this happen to them, and it seems to be random as
to which ones drop. Calls that dial out on either T1 and calls that come in
and are not redirected never seem to have these problems.

I have callprogress=no and busydetect=no but that doesn't seem to help.

Anyone have an idea on this?

Is there any way to make Asterisk less sensitive to hangups if that's even
the cause?

Just looking for some feedback before I post on the bugtracker.

Thanks,

MATT---