I own a big rental house on the outer banks. A lot of the renters are requesting a intercom because it is nearly impossible to communicate between floors, and with the kitchen and the living room being on the top floor you have to walk up 3 flights of stairs to talk to people. I need an intercom, but it needs to be wired, because I heard the wireless ones are not very good, and they will be pretty far away from earth other. I was thinking I might be able to do something with the phone lines in the house. Our phone system only uses two of the four wires in the line, and there are already phone lines in every room. Is there a way to wire an intercom with the two extra wires in the phone line?