Zap channels not clearing

Evening all.
I’ve just set up my first Asterisk server, and it works really well.
Today, we went live and started using the system to handle real calls.
All was well until I noticed that some of the ZAP channels were remaining open after the calls ended.
The setup I have is as follows:
O/S: Fedora Core 4
Hardware: 2 x Digium TDM400P
(Board 1: 4 x FXO, Board 2: 2 x FXO 1 x FXS)
5 x Grandstream GXP-2000 (latest firmware)
1 x Grandstream HandyTone 486 V2 ATA
1 x Analogue phone connected to FXS port.
5 x POTS lines into Digium cards - BT FEATURELINE

We are all able to make and receive calls without problems, but occasionally some of the channels remain active.
The only way I can tell this is to run zttool, which says Total/Conf/Act 4/3/2 - even when no calls are in operation.
Any info on how to either confirm if these channels are actually still active or how to force them to close would be appreciated.
If it’s relevant, I’m based in the UK using BT FeatureLine analogue lines (all “Featues” have been turned off.).
One hint… when placing an inbound call and hanging up before it’s answered, Asterisk doesn’t terminate the call until it ends up in voicemail and times out due to silence - any tips, please???

sounds fairly normal for a UK setup :smiley:

are you loading wctdm with opermode=UK options set ? what does your zapata.conf look like ?