Just to amplify the "you're in way over your head", any phone system can handle Caller ID display to the phones, and I suppose there are some systems that have "voice mail to email" capabilities, you have been sucked into the "digital PC based" hole. Off the top of my head, I can think of about 3 systems that you don't have to be a dealer to install, but you damn well better know what you're doing.
Clearly you don't so I suggest with the others that you hire someone who knows what they're doing. Your "friend" isn't doing you any favors.
Carl
