I have a BCM50 that has an old style T-1 which of course provides no caller ID info. I noticed that it looks like the MBM in the EXP bay is the same that is used for a PRI. It even says that it is a DTI. Does a T1 and PRI use the same MBM? If I have the phone company switch them over to a PRI do I just change the type of service used on the MBM change it from T1 to PRI? Will my DN programming i.e. DID's Lines, features buttons remain or will I have to reprogram. They have 12 sets so no big deal. How about voice mail and AA?