touch-tone dialing

Touch-tone dialing is a method used to input telephone numbers using a telephone keypad. Each number (0-9), plus the '*' and '#' keys, is associated with specific audio tones called Dual-Tone Multi-Frequency (DTMF) signals. When a key is pressed, the phone generates two distinct audio frequencies simultaneously, which are sent over the phone line to the telephone exchange. The system recognizes these tones to identify the digits dialed, enabling features like direct dialing, automated menus, and data transmission. This method replaced rotary dialing, offering faster and more reliable input.