Western Electric 1500 TouchTone Phone w/ 10-button keypad, circa 1960s (T527) | #1855067626
Squaring the Circle: 15 Telephone Keypad Layouts that Could Have Been - 99% Invisible
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Modern touch-tone phones generate and detect | Chegg.com
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Touch tone telephone key pad for Western Electric, Stromberg Carlson and ITT telephones such as the 2500and 2554 model | Phone Shop
Answered: When a key is pressed on a touch-tone… | bartleby
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