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System X (telephony)
System X is the digital switching system installed in almost all telephone exchanges throughout the United Kingdom, from 1980 onwards. History Development System X was developed by Post Office Telecommunications (later to become British Telecom), GEC, Plessey, and Standard Telephones and Cables (STC), and was first shown in public in 1979 at the Telecom 79 exhibition in Geneva, Switzerland. STC withdrew from the project in 1982. In 1988, the telecommunications divisions of GEC and Plessey merged to form GPT, with Plessey subsequently being bought out by GEC and Siemens. In the late 1990s, GEC acquired Siemens' 40% stake in GPT. GEC renamed itself Marconi in 1999. When Marconi was sold to Ericsson in January 2006, Telent plc retained System X and continues to support and develop it as part of its UK services business. Implementation The first System X unit to enter public service, in September 1980, was installed in Baynard House, London and was a 'tandem junction unit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Switching System
In telecommunications, an electronic switching system (ESS) is a telephone switch that uses solid-state electronics, such as digital electronics and computerized common control, to interconnect telephone circuits for the purpose of establishing telephone calls. The generations of telephone switches before the advent of electronic switching in the 1950s used purely electro-mechanical relay systems and analog voice paths. These early machines typically utilized the step-by-step technique. The first generation of electronic switching systems in the 1960s were not entirely digital in nature, but used reed relay-operated metallic paths or crossbar switches operated by stored program control (SPC) systems. First announced in 1955, the first customer trial installation of an all-electronic central office commenced in Morris, Illinois in November 1960 by Bell Laboratories. The first large-scale electronic switching system was the Number One Electronic Switching System (1ESS) of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scotland
Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjacent Islands of Scotland, islands, principally in the archipelagos of the Hebrides and the Northern Isles. To the south-east, Scotland has its Anglo-Scottish border, only land border, which is long and shared with England; the country is surrounded by the Atlantic Ocean to the north and west, the North Sea to the north-east and east, and the Irish Sea to the south. The population in 2022 was 5,439,842. Edinburgh is the capital and Glasgow is the most populous of the cities of Scotland. The Kingdom of Scotland emerged as an independent sovereign state in the 9th century. In 1603, James VI succeeded to the thrones of Kingdom of England, England and Kingdom of Ireland, Ireland, forming a personal union of the Union of the Crowns, three kingdo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISDN
Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work on the standard began in 1980 at Bell Labs and was formally standardized in 1988 in the CCITT "Red Book". By the time the standard was released, newer networking systems with much greater speeds were available, and ISDN saw relatively little uptake in the wider market. One estimate suggests ISDN use peaked at a worldwide total of 25 million subscribers at a time when 1.3 billion analog lines were in use. ISDN has largely been replaced with digital subscriber line (DSL) systems of much higher performance. Prior to ISDN, the telephone system consisted of digital links like T1/ E1 on the long-distance lines between telephone company offices and analog signals on copper telephone wires to the customers, the " last mile". At the time, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplexing
In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource—a physical transmission medium. For example, in telecommunications, several telephone calls may be carried using one wire. Multiplexing originated in telegraphy in the 1870s, and is now widely applied in communications. In telephony, George Owen Squier is credited with the development of telephone carrier multiplexing in 1910. The multiplexed signal is transmitted over a communication channel such as a cable. The multiplexing divides the capacity of the communication channel into several logical channels, one for each message signal or data stream to be transferred. A reverse process, known as demultiplexing, extracts the original channels on the receiver end. A device that performs the multiplexing is called a multiplexer (MUX), and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulse-code Modulation
Pulse-code modulation (PCM) is a method used to digitally represent analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. In a PCM stream, the amplitude of the analog signal is sampled at uniform intervals, and each sample is quantized to the nearest value within a range of digital steps. Alec Reeves, Claude Shannon, Barney Oliver and John R. Pierce are credited with its invention. Linear pulse-code modulation (LPCM) is a specific type of PCM in which the quantization levels are linearly uniform. This is in contrast to PCM encodings in which quantization levels vary as a function of amplitude (as with the A-law algorithm or the μ-law algorithm). Though ''PCM'' is a more general term, it is often used to describe data encoded as LPCM. A PCM stream has two basic properties that determine the stream's fidelity to the original analog signal: the sampling rate, which is the number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Access Network
An access network is a type of telecommunications telecommunications network, network which connects subscribers to their immediate telecommunications service provider, service provider. It is contrasted with the core network, which connects local providers to one another. The access network may be further divided between feeder plant or distribution network, and drop plant or edge network. Telephone heritage An access network, also referred to as an outside plant, refers to the series of wires, cables and equipment lying between a consumer/business telephone termination point (the point at which a telephone connection reaches the customer) and the local telephone exchange. The local exchange contains banks of automated switching equipment which direct a call or connection to the consumer. The access network is perhaps one of the oldest assets a telecoms operator would own. In 2007–2008 many telecommunication operators experienced increasing problems maintaining the quality ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PABX
A business telephone system is a telephone system typically used in business environments, encompassing the range of technology from the key telephone system (KTS) to the private branch exchange (PBX). A business telephone system differs from an installation of several telephones with multiple central office (CO) lines in that the CO lines used are directly controllable in key telephone systems from multiple telephone stations, and that such a system often provides additional features for call handling. Business telephone systems are often broadly classified into key telephone systems and private branch exchanges, but many combinations (hybrid telephone systems) exist. A key telephone system was originally distinguished from a private branch exchange in that it did not require an operator or attendant at a switchboard to establish connections between the central office trunks and stations, or between stations. Technologically, private branch exchanges share lineage with central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channel Islands
The Channel Islands are an archipelago in the English Channel, off the French coast of Normandy. They are divided into two Crown Dependencies: the Jersey, Bailiwick of Jersey, which is the largest of the islands; and the Bailiwick of Guernsey, consisting of Guernsey, Alderney, Sark, Herm and some smaller islands. Historically, they are the remnants of the Duchy of Normandy. Although they are not part of the United Kingdom, the UK is responsible for the defence and international relations of the islands as it is for the other Crown Dependency, the Isle of Man, and the British Overseas Territories. The Crown Dependencies are neither members of the Commonwealth of Nations, nor part of the European Union. They have a total population of about , and the bailiwicks' Capital city, capitals, Saint Helier and Saint Peter Port, have populations of 33,500 and 18,207 respectively. "Channel Islands" is a geographical term, not a political unit. The two bailiwicks have been administered sepa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leigh On Sea
Leigh-on-Sea (), commonly referred to simply as Leigh, is a town and civil parish within the city of Southend-on-Sea, located in the ceremonial county of Essex, England. In 2011 it had a population of 22,509. Geography Leigh-on-Sea is on the northern side of the Thames Estuary, a few miles from the open waters of the North Sea to the east, and a similar distance from the Kent coast to the south. The coastal environs of the town feature a nature reserve at Two Tree Island and a centrally located beach adjacent to Bell Wharf. At low tide Leigh's foreshore has a wide expanse of mud flats and creeks, extending offshore towards the deep water channel of the Thames (Yantlet Channel). Leigh is from central London via road and rail networks and is part of the London commuter belt. History Origins Archaeological finds of pottery and coins from Romano-British era in the locality suggest early settlement. From at least the Saxon period a hilltop clearing amidst the woodland that cove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selby
Selby is a market town and civil parish in North Yorkshire, England, south of York on the River Ouse. At the 2021 Census, it had a population of 17,193. The town was historically part of the West Riding of Yorkshire; from 1974 until 2023, it was the administrative centre of the Selby District. Selby once had a large shipbuilding industry, and was an important port on the Selby Canal, which brought trade from Leeds. History Foundation Archaeological investigations in Selby have revealed extensive remains, including waterlogged deposits in the core of the town dating from the Roman period onwards. It is believed that Selby originated as a settlement called Seletun, which was referred to in the Anglo-Saxon Chronicle of AD 779. The place name 'Selby' is first attested in a Yorkshire charter , where it appears as ''Seleby''. It appears as ''Selbi'' . The name is thought to be a Scandinavian form of Seletun, meaning ' sallow tree settlement'. Development The town of Sel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
