When an incoming call is answered by IVR or voice mail, and the caller hangs up...* will not release the line for another call for over a minute.
If an incoming call is not answered by IVR or voice mail, and the caller hangs up... * will release the call very quickly.
Is there something in the IVR/voice mail that can be adjusted to monitor the channel for disconnect?
Our POTS lines are loop start and do receive the disconnect from AT&T as they should (and tested with the analog phone with the keypad that lights up
.)
zap channels won't release 
Linear Mode
