Got some old corded phones kicking around from the days before 3 and 4 handset cordless system took over? Why not make them useful again by making an intercom from the. Growing up I remember seeing all of the 2 and 3 station intercom system in the Radio Shack magazines, I always wanted a system in our house no matter how impracticable it would have been. In about 1/2 an hour using a resistor, a battery snap, some heat shrink and a 9 volt battery you should have a great new intercom!