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dual-tone multifrequency
telephone
Learn about this topic in these articles:
Touch-Tone dialing system
- In telephone: Push-button dialing
…on a concept known as dual-tone multifrequency (DTMF). The 10 dialing digits (0 through 9) are assigned to specific push buttons, and the buttons are arranged in a grid with four rows and three columns. The pad also has two more buttons, bearing the star (*) and pound (#) symbols,…
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