Touchtone dialing was introduced by the Bell System in the United States in 1963, replacing rotary phones with push-button keypads. Each key produces a dual-tone multi-frequency signal, and the 1 key combines 697 Hz and 1209 Hz tones that telephone exchanges could decode. As phones moved into films, games and online videos, these short beeps became a universal shorthand for dialing. Creators now drop the isolated number 1 tone into edits and soundboards whenever a character starts entering a number.