Hm, number input is slow but once one is used to it it should be reliable. The problem of forgetting where you are (or being unsure if you dialed a wrong digit)

Hm, number input is slow but once one is used to it it should be reliable. The problem of forgetting where you are (or being unsure if you dialed a wrong digit) is probably mostly down to the lack of any display of the digits dialed, which isn't inherently a problem of the dial interface, and indeed earlier touch-tone phones also lacked a display. That said, the slow dial speed, and maybe the slightly higher mental effort of dialing a digit, probably do increase the chance of losing your place, or feeling as if you have.