The invention of the touch-tone keypad revolutionized phone communication by enabling direct dialing and automated systems.
The touch-tone keypad's dual-tone multi-frequency (DTMF) tones provided convenience and found applications in voicemail control and TV commercial insertion.
Deep dives
The Invention of the Telephone and the Bell Telephone Company
Alexander Graham Bell patented the telephone in 1876, leading to the formation of the Bell Telephone Company, which eventually became AT&T. AT&T struck a deal with the government to provide phone service across the United States and Canada, ensuring universal service and comparable prices for all areas.
The Evolution of Dialing and Strowger Switch
Originally, all phone calls were directed by operators who manually connected the calls. However, Strowger, a Kansas City undertaker, invented the Strowger Switch, which allowed users to dial numbers directly using buttons labeled for hundreds, tens, and units. This switch was eventually replaced by the rotary dial phone, which was faster but tied up phone company equipment for longer periods of time.
The Introduction of Touch-Tone Technology
Bell introduced the touch-tone keypad in the 1940s, using transistors to produce dual-tone multi-frequency (DTMF) tones for each key. The touch-tone keypad arranged the buttons in a grid with specific pitches assigned to each column and row. This technology brought convenience, allowed for automated answering systems, and found applications in voicemail control and commercial insertion on TV networks.
We unpack how touch tone dialing changed communication forever. Join us on a deep, quirky dive into telephone history. We’ll also deconstruct these sounds and reveal their hidden brilliance. Featuring author Annabel Dodd and telephone aficionado Jim Hebbeln of the Telecommunications History Group.