In November 1963 the Bell System introduced dual-tone multi-frequency (DTMF) technology under its registered trademark Touch-Tone telephone dialing. The technology, developed at Bell Labs, enabled calls to be switched digitally. The research leading to the design of the touch-tone keyboard was conducted by industrial psychologist John E. Karlin, head of Bell Labs’ Human Factors Engineering department, the first department of its kind at any American company.
"The rectangular design of the keypad, the shape of its buttons and the position of the numbers — with 1-2-3' on the top row instead of the bottom, as on a calculator — all sprang from empirical research conducted or overseen by Mr. Karlin.
"The legacy of that research now extends far beyond the telephone: the keypad design Mr. Karlin shepherded into being has become the international standard on objects as diverse as A.T.M.’s, gas pumps, door locks, vending machines and medical equipment" (http://www.nytimes.com/2013/02/09/business/john-e-karlin-who-led-the-way-to-all-digit-dialing-dies-at-94.html, accessed 02-10-2013).