itpphoneguy - yeah, you are being overly cautious. I once had to do a bunch of troubleshooting on voice mail, and found out that a lot of things happen "automagically" when you put and extension in hunt group 7.
Although most of these things wont show up it you go to the individual program codes and look at the extension, voice mail ports get:
-Machine Dial Tone (Intercom Dial Tone sounds like an outside dial tone)
-Intercom First on Auto Line Select
-No Immediate Ring, even though it looks like it in Centralized Telephone Programming. They only get rings when calls come to Int-777, or calls through CallDistGrp-7, after the number of rings in VMS Hunt Delay
-When calls are answered, the processor sends "mode codes", touch-tone strings of digits that indicate how to handle the call, i.e. check messages, transfer to mailbox, answer with auto attendant, etc. That's why if you forget to put a VM port in hunt group 7, it answers and after a moment says transferring to operator. It doesn't know what to do with the call.
-They will receive calls on lines that are not even assigned to the VM ports, via the CallDistGrp-7 programming, but if you want to have outcalling, you need to assign lines for that to happen.
I'm sure they're other things that happen, but that's all I can think of off the top of my head. I picked up a digit grabber from e-bay, and sometime I'll figure out what all the different mode codes are, just for information's sake.