I have a T1 CAS (nowhere close to a PRI)
It has 24 channels used for Voice / FAX / General VM. When calls are made outside, calls go out of the available channel and displays the number of the channel.
e.g. I dial a phone, the next available line was a fax line and it dials out, when the caller redials they get a fax tone.
IS THERE A WAY TO MASK THE CALLER ID on a T1 CAS.