I've just read a few other comments here and it seems that I might be a little older than most of the HN commentards, these days.
When I was a lad you put your finger into the bottom left hole of a rotary dial and moved the dial clockwise until it was over the chosen number. You then released your finger and allowed the dial to roll back to null. You then dialled the next number etc
You did not press keys. That is why 999 was chosen. Telephones with rotary dials had obvious clues to where the home "hole" was - where you would dial from - and you would hit the backstop when you hit nine when you rotated the dial.
When I was a lad you put your finger into the bottom left hole of a rotary dial and moved the dial clockwise until it was over the chosen number. You then released your finger and allowed the dial to roll back to null. You then dialled the next number etc
You did not press keys. That is why 999 was chosen. Telephones with rotary dials had obvious clues to where the home "hole" was - where you would dial from - and you would hit the backstop when you hit nine when you rotated the dial.
It's not rocket science 8)