In the late 1960's, in Johannesburg, my friends and I discovered a "hack" for payphones. In those days and at that place, people paid per-phone-call, so finding

In the late 1960's, in Johannesburg, my friends and I discovered a "hack" for payphones. In those days and at that place, people paid per-phone-call, so finding a way to call for free was great for a bunch of crazy teen-agers. What we discovered was that you could use a grounded wire to fool the phone company into thinking a coin was dropped into the coin slot. When the recording said "please deposit ..." we would scratch the wire to a metal part of the mouth piece. (There was a small hole in the plastic of the mic for some reason - that is what we used). The "ground" was the metal cage on the overhead light. For some reason, the scratch produced simulated the signal of a coin drop. Many silly school-boy prank calls ensued. I hang my head in shame.