Look into a phone line switch between your computer and your telephone. Unless you are actually dialed up and on line, you do not want to be electrically connected to your phone line. A simple disconnect box on your desk would work.
There are many reason to do this. First, if you live where I do, lightning is always a threat to phone lines, and it is not good to leave them hooked to the computer. Second, it guarantees that incoming calls will not send a voltage to your computer.
When I was on dialup, I used an automatic call director. The line plugged to it, then it connected to the phone and to the computer and an asnwering machine. No incoming calls went to the computer. They were either directed to the phone or the fax.
