A telecommunication signaling system uses the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. Developed in the Bell System in the United States, it became known under the trademark Touch-Tone for use in push-button telephones, starting in 1963. The DTMF frequencies are standardized in ITU-T Recommendation Q.23. The signaling system is also known as MF4 in the United Kingdom, as MFV in Germany, and Digitone in Canada.
How It Works
The system uses combinations of two audio frequencies, one from a low group and one from a high group, to represent digits 0-9 and other control functions. Touch-tone dialing with a telephone keypad gradually replaced the use of rotary dials and has become the industry standard in telephony to control equipment and signal user intent.
Applications
- Telephone dialing: The most common use of DTMF is for dialing on push-button telephones.
- Automated systems: Used in interactive voice response (IVR) systems for menu selection and data entry.
- Remote control: DTMF tones can control devices such as alarms, lights, and other systems over telephone lines.
Regional Variations
- MF4: The term used in the United Kingdom.
- MFV: The term used in Germany.
- Digitone: The term used in Canada.