Kyle may have something. I remember something about certain issue channel units for SLC96 that had problems passing CID. Also, is there any way that you can get the LEC to swap the cable pairs between the working CID & the one that doesn't work just to see if it makes a difference. I seen problems where bridge-tap or loading or a slight unbalance would block CID to a good quality phone but a cheap analog CID box worked just fine.

Gary