It pretty much depends upon the type of phones you're using. If they are IP phones, then you only need to either have power outlelts for them or a POE network switch. Since it's an existing system, I doubt that will be an issue.

If the phones are digital, keep in mind that they use the second pair in the wiring, not the first like most other systems. Many slackers will often wire jacks with only the first pair to save time. If that's the case, you'll need to rewire the jacks or purchase modified line cords to adapt. Normally, this isn't the case, but it does happen, especially late on Fridays.

Ed Vaughn, MBSWWYPBX