@internetsdairy @graham_knapp It was definitely a feature - the idea of using 1-1-1 1-1-2 or similar was dismissed because not so much that it was accidentally dialled by a user with a phone, but that interference or hung cables tapping together could much more easily 'dial' those patterns. Given the time period, being 3 human-dialled digits was quick, the extra maybe 0.5s per digit wasn't a significant period of time. As other countries copied the idea later, systems were better understood.