When I was a lad, we didn't have your fancy smartphones. We didn't have mobile phones at all, which meant there was much greater need for public payphones and they were consequently more numerous. The funny thing was, there was a way to use payphones without actually paying.
My friends and I called it "tapping" the phone. This didn't mean eavesdropping on someone else's conversation, but literally tapping on the phone.
It worked like this: rather than dialling the number conventionally using the rotary dial, you lifted the receiver, subtracted the number you wanted to dial from 10 and tapped on the cradle that number of times. So to dial a three you tapped seven times. And to dial the number 584 273, you tapped 5-2-6-8-3-7. Zeroes could be dialled. No coins required.
It nearly always worked, and I've never found out how. I recall using it as late as 1981, when, in my first year as a newspaper reporter, I had to file a report from a rugby match and found myself without change for the phone box.
That was about six years after the introduction of STD, so maybe we could have directly dialled the Vatican, like Steve Jobs and Steve Wozniak did with their famous Blue Box (it was watching an old interview with Jobs last night on Netflix that got me thinking about this). But it never occured to us to make anything but a local call.
So, does ayone know how and why this worked? Decades later, it still intrigues me.