Anchor Exchange was an underground, hardened telephone exchange built in Birmingham, England.
Anchor Exchange was an underground, hardened telephone exchange built in Birmingham, England.
Construction commenced in 1953 under the guise of building an underground railway. It opened in September 1957 at a cost of £4 million. [1] It was located nominally on Newhall Street. [2] [3] However its network of tunnels extended from at least the Jewellery Quarter to Southside. [4]
It originally formed one of a network of 18 zone switching centres within the UK telephone system that provided trunk switching facilities within its own charge group and to group switching centres (GSC) within an area broadly comprising the West Midlands and central Wales. The exchange formed part of the trunk mechanisation plan commenced in 1939 [5] to permit operators from originating GSCs to dial through to a distant UK subscriber without requiring further operator intervention. Later, it was additionally used to switch subscriber dialled trunk calls after its introduction at Bristol in 1958.
It was subsequently augmented and superseded by a transit switching centre (TSC) equipped with a crossbar switching system (TXK4) which formed part of the transit network. It parented two of the first three GSCs at Worcester and Wolverhampton [6] to go live when the transit network was inaugurated in 1971 which eventually provided universal UK automatic subscriber dialling and was completed in 1979. [7]
The Anchor telephone exchange tunnels are still used to house communication cables. They have been updated with firebreak compartments and hazardous asbestos has been removed. They are continually pumped out because of the city's rising water table. [4]
The exchange took its name from the hallmark of Birmingham Assay Office, which depicts an anchor.
The exchange is notable for being one of three, along with the Kingsway Exchange in London and the Guardian Exchange in Manchester, which provided hardened facilities in order to protect communications in the event of a nuclear attack during the Cold War in the UK (a fourth one was rumoured to exist in Glasgow, but no evidence of this has been found). [8] In common with most civil defence structures of the time it was designed to withstand an attack by an atomic bomb short of a direct hit. By the time of its completion in 1957, the development of thermonuclear weapons with their significantly increased explosive power, would have reduced the ability to resist an attack. [9]
The public was told that the project was to provide the city with a new underground rail network, but that by 1956 the project was no longer needed due to costs. [8] There was an entrance at the rear of Telephone House, between Lionel Street and Fleet Street, where there was a strict security check upon entering; this entrance had a heavy blast door weighing about two tonnes. [8] Another entrance was on Newhall Street.
Guardian Exchange was an underground telephone exchange built in Manchester from 1954 to 1957. It was built together with the Anchor exchange in Birmingham and the Kingsway exchange in London – all believed to provide hardened communications in the event of nuclear war; as well as linking the UK government in London to the US Government in Washington, D.C. by means of a secure and hardened transatlantic telephone cable making landfall near Oban and running through Glasgow, Manchester and Birmingham. Today, the underground site is used for telephone cabling. Constructed at a depth of below 35 metres (115 ft), the tunnels are about 2 metres (80 in) in diameter. The exchange cost around £4 million, part of which was funded by the United Kingdom's NATO partners.
Subscriber trunk dialling (STD), also known as subscriber toll dialing, is a telephone numbering plan feature and telecommunications technology in the United Kingdom and various Commonwealth countries for the dialling of trunk calls by telephone subscribers without the assistance of switchboard operators.
Kingsway telephone exchange was a Cold War-era hardened telephone exchange underneath High Holborn in London. Initially built as a deep-level air-raid shelter in the early 1940s, it was instead used as a government communications centre. In 1949 the General Post Office (GPO) took over the building, and in 1956 it became the UK termination point for TAT-1, the first transatlantic telephone cable. Closure of the facility began in the 1980s. It was built together with underground exchanges in Birmingham and Manchester, and was originally covered by a D notice
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The director telephone system was a development of the Strowger or step-by-step (SXS) switching system used in London and five other large cities in the UK from the 1920s to the 1980s.
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System X is the digital switching system installed in almost all telephone exchanges throughout the United Kingdom, from 1980 onwards.
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Telephone numbers in Turkey went from six (2+4) to seven digits (3+4) local phone numbers c.1988, at which time Ankara went from 41 to 4. There used to be more than 5,000 local area codes of varying lengths with correspondingly varying local number lengths.
17 & 19 Newhall Street is a red brick and architectural terracotta Grade I listed building, situated on the corner of Newhall Street and Edmund Street in the city centre of Birmingham, England. Although its official name is 17 & 19 Newhall Street, it is popularly known as The Exchange, and was previously known as the Bell Edison Telephone Building.
020 is the national dialling code for London in the United Kingdom. All subscriber numbers within the area code consist of eight digits and it has capacity for approaching 100 million telephone numbers. The code is used at 170 telephone exchanges in and around Greater London as part of the largest linked numbering scheme in the United Kingdom. In common with all other British area codes the initial '0' is a trunk prefix that is not required when dialling London from abroad.
A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices for data transmission via the public switched telephone network (PSTN), or other public and private networks. Modern smart phones have added a built-in layer of abstraction whereby individuals or businesses are saved into a contacts application and the numbers no longer have to be written down or memorized.
PSTN network topology is the switching network topology of a telephone network connected to the public switched telephone network (PSTN).
A telephone exchange, also known as a telephone switch or central office, is a crucial component in the public switched telephone network (PSTN) or large enterprise telecommunications systems. It facilitates the interconnection of telephone subscriber lines or digital system virtual circuits, enabling telephone calls between subscribers.
A group switching centre (GSC) was a United Kingdom telephone exchange used to provide local and trunk routing to local exchanges within its own and if required, adjacent group areas.
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