I have a wctdm24xxp that is having some problems interfacing with a Cisco IAD(the IAD is the telco). It seems that after several incoming calls the card simply stops accepting incoming calls or dialing outgoing calls. A plain old telephone also on the line rings properly etc.

modprobe wctdm24xxp -r
modprobe zaptel -r
modprobe wctdm24xxp

the above does not fix the problem. However, rebooting does (no way to kill power to the card w/o rebooting, so I suspect, but cannot confirm that this is what is solving the the problem).
Does anyone know what the cause of this could be?

Also is there a utility out there that show the voltage across the channels on the card or something similar (zttool seems rather limited in it’s functionality)?