TELEPHONEKEYPAD
Telephone keypad
A telephone keypad is a keypad that appears on a "Touch Tone" telephone. It was standardised when the dual-tone multi-frequency system in the new push-button telephone was introduced in the 1960s, which gradually replaced the rotary dial. The invention of the keypad is attributed to John E. Karlin, an industrial psychologist at Bell Labs.The above text is a snippet from Wikipedia: Telephone keypad
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