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A typical rotary-dial key telephone: the Western Electric eighteen-button Call Director, manufactured from 1958 to the early 1980s. Before the development of large-scale integrated circuits, key systems typically consisted of electromechanical components, such as relays, as were larger telephone switching systems.
The most commonly used telephone sets for the 1A2 systems were modifications of the Bell System standard 500-series telephones for rotary dial systems, and the 2500-series Touch-Tone desk sets. For key system operation these sets were equipped with a set of push-buttons ( keys ) and additional internal contact springs to control the additional ...
A telephone network is a telecommunications network that connects telephones, which allows telephone calls between two or more parties, as well as newer features such as fax and internet. The idea was revolutionized in the 1920s, as more and more people purchased telephones and used them to communicate news, ideas, and personal information. [ 1 ]
Overall, a basic telecommunication system consists of three main parts that are always present in some form or another: A transmitter that takes information and converts it to a signal A transmission medium , also called the physical channel, that carries the signal (e.g., the "free space channel")
Plain Old Telephone Service (POTS), or Plain Ordinary Telephone System [1], is a retronym for voice-grade telephone service that employs analog signal transmission over copper loops. The term POTS originally stood for Post Office Telephone Service , as early telephone lines in many regions were operated directly by local Post Offices .
A typical volume of Bell System Practices from the 1970s. The Bell System Practices (BSPs) is a compilation of technical publications which describes the best methods of engineering, constructing, installing, and maintaining the telephone plant of the Bell System under direction of AT&T and Bell Telephone Laboratories. [1]
An optical communication system is any form of communications system that uses light as the transmission medium. Equipment consists of a transmitter, which encodes a message into an optical signal, a communication channel, which carries the signal to its destination, and a receiver, which reproduces the message from the received optical signal.
A mobile phone or cellphone or hand phone is a handheld telephone which connects via radio transmissions to a cellular telephone network. The cellular network consists of a network of ground based transmitter/receiver stations with antennas – which are usually located on towers or on buildings – and infrastructure connecting to the global ...