Well, it's been over a week and I went back there on other business and it's still happening.

I dialed "9" and got line 18 (it starts @ line 108). I then went into maintenance to check the busy/idle state of a few lines and they were "unavailable" (as opposed to again busy or idle).

SO...what I had hoped was the problem is actually a symptom that can be fixed in the short run by de-provisioning & re-provisioning the channels one by one, or resetting the cards one by one, or probably the entire system.

What could be causing 2/3's of the total channels across 3 T-1's to lock up?.....

Can't be bad cards because it's on all 3 T's.....maybe S/W corruption or telco is all I can guess.

Punch down all your damn pairs!..........(please).