It would be helpful to know from where the OP is installing this. In PA, you MUST have a copper dedicated phone line. A lot of places try and get away with using a shared line, but if the elevator inspector detects it, he will demand the line be dedicated. We, at one time, used a device made by Viking that allowed two elevators to share one line and, to my surprise, was OK with the inspector. Recently, I had to provide a line for a new elevator and the elevator inspector made me walk him to the Demarc to prove there was nothing else connected to the line.
Rcaman