Yes, either not receiving release supervision or not releasing. That is why I said have telco see what they see on the trunks, they can also set up a trap to see when and why they fail, trap will come from supplier of the trunks. Also Tberd makes a great test set that will break out each channel and can be hooked up to a printer, they are expensive so maybe you can find a tech in your area that has one, might even get lucky and have telco put one on for you, but I doubt it.
Bill


Retired phone dude