Howtosignalprocessing
What is DTMF tones in call settings?
Dual tone multi frequency (DTMF) is a technology used with touch tone phones, best known to users as the sound made when pressing a number key. It signals the phone company that you want to make a call and sends a command to the switch.
What is DTMF tone detection?
DTMF technology works by having the handset generate tones at specific frequencies and playing them over the phone line when a button is pressed on the keypad. Equipment at the other end of the phone line listens to the specific sounds and decodes them into commands.
What frequency are DTMF tones?
The DTMF keypad for consumer use is designed in a four-row by three-column matrix. Each dial row is represented by a low tone frequency and each column by a high tone frequency. The frequencies used are 697 Hz, 770 Hz, 852 Hz, 941 Hz, 1209 Hz, 1336 Hz, 1477Hz, and 1633 Hz.
