I have been fighting this for about a month . An SX50 worked fine on loop start copper trunks from the telco. Now on a T1 line. Still loop start lines from the Adtran channel bank but now about twice a week the trunks fail to release and then cant dial in or out. Pulling the Amp connector from the trunk card causes the trunks to drop and every thing works fine till the next time they fail to release. The channel bank is dropping the voltage on the trunks when the calling party hangs up. I have put SX-50s on channel banks many times before with no problems. Anybody have any ideas on what I may have done wrong this time?

Change last line to read " Anybody have any ideas on what may be wrong." I dont think I did anything wrong!

Let me guess, motel. How hot does the equipment room get? The obvious 1st step is to swap out the LS/GS card(s). Next, or maybe FIRST is suspect channel bank! Do the trunk card first, because then you can say that changing out your equipment made no change and it was ok before the T1. And you might shorten the disconnect timing recognition. Reg 2, Bit f, for each trunk. If the customer has no use for conference, disable trunk to trunk conference.
And change disconnect supervision guaranteed to no, Reg 2, Bit c. And in Reg 1 make sure you are set to short analog trunk.

Yes it is in a motel but this switch was lucky enough to be mounted in the managers office. He keeps it about 70 degrees in there all the time. I have changed the trunk card and the channel bank has also been changed. I will make the adjustments in the programming that you suggested and see what happens. Thanks