> You click the handset down, like you are hanging up the phone, but just very briefly.

This brings back memories, this is a trick people my age group mastered as teenagers in a 3rd world country. All calls were billed - including local ones, so parents would commonly get lockable cages that would cover the buttons/rotary dial to prevent unauthorised calls in their absence. The cages would leave the receiver accessible even when locked in order to be able to receive calls, so we would use the hook to do pulse tone dialing; dialing a number with many zeroes was always a challenge since it required 10 rapid taps as part of a longer sequence, but I built up muscle memory.

The practice was colloquially named 'tap-dialing' and it was handed down from generation to generation. Sadly it came to an end in the smartphone world.