[asterisk-users] Zap channels hang

[Dale Wilcox]

Please be gentle with a newbie...
I'm working with a vendor to implement an Asterisk / Trixbox system in
a 2 location small business.
We're transitioning from an Avaya Legend / Magix infrastructure with
T1 PRI network access to sip trunk to the public network and an IAX2
trunk inter-office. PRIs connect the Asterisk and Avaya systems to
support extensions that remain on the old Avaya equipment. I have 1
queue with 4 extensions on Asterisk with Polycom 501 handsets.

Asterisk 1.4.18
FreePBX 2.4.0.0
TrixBox 2.0.0.1

We're running into an ocasional problem with ZAP channels hanging on a
dual T1 Sangoma card.
It seems to be a user problem with assisted transfers on Polycom 501 phones.
User presses transfer, dials the IP extension, presses send, doesn't
wait for the call to complete, and sends the caller.

The way it played out:
I needed to review and commit an IVR I had set up several days ago.
Launched Trixbox, switched to maintenance user and clicked the FreePBX
menu, extremely slow response from the server but eventually the
FreePBX main screen loaded. That was as far as I got.

Started an SSH session to check server status
sip show peers
sip show queues
zap show channels

show channels  would stop on channel 16 most of the time, hanging the
terminal, other times it would complete.
show queues showe and active call on 2 sip extensions (for the rest of
the day until restart). FOP also displayed both extensions busy but
they did continue to receive calls

A call had come in over copper through the Avaya and was transfered
over PRI to Asterisk to a sip extension then transfered to a second
sip extension (incorrectly) and died.

Once this situation starts, the only way to correct is restarting the
asterisk service.

Vendor says it's a new problem to them because all of their other
systems are sip and iax2 only, no zap.

Possibly a version or module upgrade that is more forgiving of users
or maybe the transfer issues are just coincidence?

Other thoughts?

Kinda stuck here
Dale