Reminds me of the good old bakelite phones they had in public call boxes when I was a kid (in Britain 1960s-70s).
Basic cost of a call (in my time) was 4 pennies (pre-decimal) but (and please don't report me for fraud) if you dialled the number and, while the dial was returning to its original position, you tapped the (single) cradle up and down as many (or more) times than the individual number just dialled and, if you did it right, you'd get the call for free!
When they were replaced with plastic dial phones the cradle had a left and right hand side and you just could not tap them at exactly the same time to get the free calls.
Basic cost of a call (in my time) was 4 pennies (pre-decimal) but (and please don't report me for fraud) if you dialled the number and, while the dial was returning to its original position, you tapped the (single) cradle up and down as many (or more) times than the individual number just dialled and, if you did it right, you'd get the call for free!
When they were replaced with plastic dial phones the cradle had a left and right hand side and you just could not tap them at exactly the same time to get the free calls.






















