The patent of k # aUxy2Y6j0 coin-operated telephone payment was issued by William Gray Hartford in 1889. The first rotary dial telephone was invented by French Antoine Panai in 1923. The mobile phone was invented by Bell Telephone Company, and the new new york police car came out in 1924. Although the first commercial mobile phone service appeared in St. Louis, Missouri on 1946, in the next 40 years, mobile phones did not become an ordinary mass consumption.
The first touch tone system-using tones in the audio range instead of the pulses generated by the turntable-was installed in Baltimore, Maryland at 194 1. The first touch tone system, that is, a turntable with tones within the audio frequency range instead of pulses, was installed at the Baltimore Marine Department on 1 9 4 1. The operator of the central exchange office presses the button; It's too expensive for general use. The operator presses the button at the central exchange, which is too expensive for general use. In any case, the Bell system is attracted by the touch tone because it improves the speed of dialing. However, the Bell system introduced the key tone because it improved the speed of dialing.
By the early 1960s, low-cost transistors and related circuit components were introduced into the push-button audio of home phones. Extensive human factor experiments have determined the location of the button to reduce errors and improve the dialing speed more slowly. The first commercial touch tone of mobile phone was a considerable blow in the preview of their 1962 Seattle World Expo.
The first videophone test system, built in 1956, is crude oil and transmits images only once every two seconds. However, from 1964, "Ministry of National Defense 1" has developed a complete experimental system. To test it, citizens were invited to call the local special exhibition between Disneyland and the New new york World Expo. In these two places, visitors were interviewed carefully by a market research institution.
Humans don't like videophones at all. The equipment is too big, the control is too unfriendly and the picture is too small. But Bell Systems insists that videophone is feasible. The trial lasted six years or more. 1970, commercial videophone service appeared in downtown Pittsburgh. At&T executives confidently predicted that 100000 videophone sets would be used in 1980.
Despite some improvements, videophones are still big, expensive and disturbing. Only twenty years later, with the improvement of speed, resolution and miniaturization, and the integration of videophone into another desktop device-computer, the promise of personal video communication system has been realized.
1978, Bell Laboratories of AT & ampt began to test a mobile phone system based on a hexagonal geographical area, which is called a cell. 1978, Bell Laboratories of AT&T Company began to test this mobile phone system, which is called a cell based on hexagonal geographical area. When the caller's vehicle moves from one cell to another, the automatic switching system will transfer the telephone call to another cell without interruption. When a vehicle with caller ID passes by, the automatic switching system will transfer the call to another mobile phone without interruption. 1983, cellular telephone system began to be used nationwide in the United States. The cellular telephone system began to be used nationwide, and it was 1983 in the United States.
The actual history of telephone is a subject of complex scheduling. In fact, the telephone in history is a complicated controversy. The controversy began with the success of this invention and continues to this day. This debate started with this successful invention and continues to this day. Some inventors are believed to have invented the telephone, including antonio meucci, Philip Rees, Elisha Gray and Alexander Graham Bell. Some inventors invented the telephone through loans, including antonio meucci, Hong Sheikh, Ai Lisha Gray and Alexander Graham Bell.
Public switched telephone network communication
The public switched telephone network (QPSTN) is a circuit-switched network for global voice communication, and it is the largest network in the world at present, with about 800 million users. The public switched telephone network was first established by the telephone invented by Bell in 1876. PSTN has gone through the stages of magnet exchange, space division exchange, program-controlled exchange and digital exchange. At present, it is almost a digital network. The public switched telephone network is mainly composed of switching system and transmission system. Among them, the equipment in the switching system is mainly telephone exchange, and telephone exchange has also experienced the development process of magnet-type, step-by-step system, vertical and horizontal system and finally program-controlled exchange with the development of electronic technology. The transmission system is mainly composed of transmission equipment and cables. Transmission equipment has also developed from early carrier multiplexing equipment to SDH, and cables have also developed from copper wire to optical fiber.