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Multifrequency signaling is a technological precursor of dual-tone multi-frequency signaling (DTMF, Touch-Tone ), which uses the same fundamental principle, but was used primarily for signaling address information and control signals from a user's telephone to the wire-center's Class-5 switch. DTMF uses a total of eight frequencies.
Dual-tone multi-frequency signaling ( DTMF) is a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers. [1] DTMF was first developed in the Bell System in the United States, and became known under the trademark Touch-Tone for use ...
The series was called the Design Line telephones. The name did not refer to one particular telephone type; rather Design Line was the collective name given to all the specialty phones, including the Candlestick phone, Country Junction phone, Mickey Mouse phone and others. [1] The phones were among the few that could be purchased in the early 1970s.
Ericofon. The Ericofon is a one-piece plastic telephone created by the Ericsson Company of Sweden and marketed through the second half of the 20th century. It was the first commercially marketed telephone to incorporate the dial and handset into a single unit. Because of its styling and its influence on future telephone design, the Ericofon is ...
A push-button telephone is a telephone that has buttons or keys for dialing a telephone number, in contrast to a rotary dial used in earlier telephones. Western Electric experimented as early as 1941 with methods of using mechanically activated reeds to produce two tones for each of the ten digits and by the late 1940s such technology was field ...
A 220 Trimline rotary desk phone, showing the innovative rotary dial with moving fingerstop Early Touch Tone Trimline with round buttons and clear plastic backplate and round non-modular handset cord Redesigned touch-tone desk model Trimline, manufactured on January 9, 1985 The Trimline 2225, one of the last phones made at the Indianapolis Works in 1986 Early foreign made Trimline, December ...
The Western Electric 500-type telephone replaced the 300-type, which had been produced since 1936. The model 500 line was designed by the firm of industrial designer Henry Dreyfuss, the product of several years of research and testing in collaboration with Bell Laboratories and Western Electric. Development started in 1946 with early sketches ...
The Trimphone is a model of telephone designed in the early 1960s in the UK, the first prototypes appearing in 1965. It was positioned as a more fashionable alternative to the standard telephones available from the Post Office Telephones, the nationalised predecessor to British Telecom. The name is an acronym standing for Tone Ring Illuminator ...