DTMFäänimerkkien

DTMF (Dual-Tone Multi-Frequency) digits, often referred to as touch tones, are a series of audio frequencies used in telecommunications to signal dialed numbers. When a button on a telephone keypad is pressed, two specific tones are generated simultaneously. One tone represents the row the button is in, and the other represents the column. These dual-tone combinations are unique for each digit and symbol on the keypad. For example, pressing the '1' key produces a combination of 697 Hz and 1209 Hz. Similarly, '5' generates 770 Hz and 1336 Hz, and the '*' key produces 941 Hz and 1209 Hz. These tones are designed to be easily distinguishable from voice frequencies, allowing telephone switching systems to interpret the dialed digits accurately. DTMF technology replaced older pulse dialing systems, significantly speeding up call establishment and enabling features like automated menus and interactive voice response (IVR) systems. The DTMF standard was developed by Bell Labs in the 1960s.