AT&T unless things have change a lot since I retired should be able to give you both the AT&T id and the local id, I know we always had access to both in the maintenance center. If you've told them you are switching carriers they will probably only give you the information they are require to.

The 68hcgs are the local id's for the t-1 BUT they will probably only talk to who order the circuits which was AT&T so you're in a catch 22, you bought the service from AT&T who ordered the local access so AT&T is the local carriers customer not you. I don't know why the local company wouldn't tell you who the circuit id's belong to at the very least.

If you have the bills and the local company isn't charging you for a T-1 then they must all be AT&T's. I'd still get my vendor out for help.

Retired phone dude