Re: Pulse dialling?
Clicking the handset rest* was a way to make free calls from pre-STD** call boxes.
IIRC, to make calls legally, you had to insert four pre-decimal pennies, things about the size and weight of a bronze coaster, dial the number, and when you were connected, press Button A to commit the transaction. There was a Button B for rollback. I suppose the phone wouldn't transmit dial pulses until you proved you had the money, but the line was enabled so you could simulate them by clicking the receiver rest.
It sounds like the Middle Ages, especially when you realise that the four pennies we saved were worth 1.7p in decimal money.
*known, confusingly as "phone tapping"
**Subscriber Trunk Dialling, not Sexually Transmitted Disease