I work on ph lines everyday for my business, it shld plug straight in and it cannot damage your telephone line, or the 12 volt line cannot damage it...
....all standard phones work on 12volt 2 pair.
Inside your home line, there are 4 wires, 1 x pair is blue-white, the second pair is red-black.
Blue and white is usually your first phone line.The second pair is for your second ph line, if u want one etc.
Plug it in.no big deal. provided it has the standard socket, it shld work easily.take a photo of the plug n send it to me if ya want...i can tell ya in 3 seconds.