What makes more sense? PRI or DID Trunking? Any experience in this area out there?
Neither but if I had to take the better of two evil's. Go PRI
I agree with the above statement in the fact that someone has deep pockets.
I would never suggest a PRI or DID for such a small application(unless i was ripping someone off).
Scratch the CISCO and leave the PBX. Use POTS for the vault, 911 and fax and dedicate two lines for your "DID". Change the extension numbers to match the last four of the "DID" and set the lines to ring only those extensions. Make the lines private to those extensions and set up auto select for those trunks.
Fair warning if you are going to run the vault through the system you better check your local code. POTS carries its own voltage and if your system goes down you wont be disrupting service. During an emergency there is a very high likelyhood that power will be lost in the building. You dont want to be the guy looking at a lawsuit because someone could not call out for help.
