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The new system replaced the older hard-wired system, which came in many 'flavours' (e.g., Plans 1, 1A, 1B, 1C, 2, 2A, 105, 107 etc.), which could be very complicated and required the attendance at the premises of a GPO telephone-engineer, who needed a complete set of 'N' (wiring) Diagrams, [7] [better source needed] which was very extensive and ...
Cooke and Wheatstone's five-needle telegraph from 1837 Morse telegraph Hughes telegraph, an early (1855) teleprinter built by Siemens and Halske. Electrical telegraphy is a point-to-point text messaging system, primarily used from the 1840s until the late 20th century.
Utility pole with electric lines (top) and telephone cables. Fixed telephone lines per 100 inhabitants, 1997–2007. Cross section of telephone cable of 1,800 twisted pairs, 1922. A telephone line or telephone circuit (or just line or circuit industrywide) is a single-user circuit on a telephone communication system. [1]
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 telephone jack and a telephone plug are electrical connectors for connecting a telephone set or other telecommunications apparatus to the telephone wiring inside a building, establishing a connection to a telephone network.
A SP1 2-wire variant was also available that provided Centrex services. A version of the SP-1 ESS that could provide both 2 & 4 wire services was also built. The first instance was installed in Vegreville Alberta in 1976 or 1977. SP1 4-Wire (Toll) The first example of this switch was installed for Bell Canada, in Thunder Bay, Ontario in late 1973.
One wire circuits were typically called earth return circuits, or sometimes 'non metallic' and two wire were also referred to as 'metallic circuits'. Metallic referring to a total metal (copper or steel) circuit for both legs of the circuit. [1] This basic telephone circuit was known as a Buzzer, or more commonly, a Condenser Telephone Circuit. [2]
A telephone switch is the switching equipment of an exchange. A wire center is the area served by a particular switch or central office. A concentrator is a device that concentrates traffic, be it remote or co-located with the switch. An off-hook condition represents a circuit that is in use, e.g., when a telephone call is in progress.