Wood Street ITSC
...rings the world
Wood Street rings the world...
Wood Street, a brand new ITSC (International Telephone Services Centre), built next to Wood Street Telephone Exchange, opened in 1972 and was fitted with TXK2 equipment, the ATE 5005T manufactured by Plessey. It was described as a 'modern 4-wire gateway international exchange.'

Image: Wood Street rings the world.
| EXIT | Wood Street | The History | The ISC | The End |
|The ICCs | Wood Street 1Wood Street 2 | INSIST | Relocation |

One of the first international exchanges opened in the Monarch ATE building as early as 1947.

During the Sixties, the growing number of calls lead to it becoming a major ITSC (International Telecommunications Switching Centre) with the installation of 'state of the art' switching equipment in the early Seventies. However, by the late Eighties, switching technology had greatly improved and thus the building was sold off and demolished during the early Nineties as land prices in London were at a premium and call centres were located away from the capital city.

The History
The first multi-unit automatic exchanges (Metropolitan, National and Empire) opened in the original Wood Street building on 13th August 1929. London Wall followed shortly after. The whole building was (bombed) destroyed on 29th December 1940.

Following reconstruction, in later years the building was home to:-

  • Monarch exchange
  • Metropolitan exchange
  • Headquarters auto exchanges
  • Continental and Assistance manual boards.
The ISC - International Switching Centre

The Relief Unit

The Strowger installation in Faraday had previously switched all the traffic to and from the UK, but was unable to keep pace with the ever increasing demand for international calls. There was little room in Faraday to expand either the manual boards or the automatic equipment. The new Wood Street building was to allow decentralisation of manual switching while catering for further growth in directly dialled calls. The building was ready by June 1970, but the switching equipment was delayed. Peter Walker, recounts..

"Wood Street relief unit was the next exchange. This was a small 5005T crossbar unit imported from previous use in Sydney, Australia. It was modified to work on London IDD traffic until Wood Street proper was ready. It was installed in a new building alongside the Wood Street local exchange. It had a capacity of around 2000e."

The relief units were installed on the 5th floor on 20th June 1970.


Wood Street proper, opened in April 1971. The building was of reinforced concrete construction with pillars at 25ft centres. No beams were used, the necessary strength was provided by heavy reinforcement of the floor slabs- a technique which provided a clear ceiling and allowed easier provision of air conditioning and overhead cabling.

The layout was:
Wood Street ISC
Sub-basement Car park
Basement Power
Ground Repeater station
1st (Podium) Offices
2nd Part of ISC and IMC
3rd Part of ISC
4th Part of ISC and IATAE
5th ICC
6th Amenities

Photo: Wood Street TE and ITSC.
Standard Features
  • The ISC, International Switching Centre comprising a Plessey 5005T Crossbar switch designated TXK2.
  • The ICC, International Control Centre handling operator connected calls.
  • The IMC, International Maintenance Centre dealing with quality of service, faults and maintenance.
  • The IATAE, International Accounting and Traffic Analysis Equipment.
  • The IRS, International Repeater Station, feeding the circuits to the network.
Wood Street had 15 IMC maintenance consoles.

Special Features
Far removed from the 21st century, CCTV 'Big Brother' series, small rack mounted cameras kept a watchful eye on the equipment in Wood Street. Continuous scanning of the images from the 6 CPIs (Call Progress Indicators) were distributed to the 15 test consoles, so that the human technicians could monitor the equipment... Call Progress Indicators (CPIs) To monitor the progress of calls through the exchange equipment, circuits could be connected via the test access system to one of six CPIs which displayed the input/output signals via filament lamps held in multi-digit indicators. Each CPI contained up to 500 lamps.

The 6 CPIs were for the following types of signals:

  • AC4 (1 set)
  • AC4 (2nd set)
  • AC10 (1 set)
  • AC10 (2nd set)
  • AC9
  • AC11
The status of the display panel of each CPI rack was relayed to the test desks via a TV camera mounted overhead on the rack tie bars.

Peter Walker explains...

"The display panels were quite large (pixie tubes, I seem to remember), so a camera was put in front of them and the picture relayed to a small VDU on the test desk. You can see this screen on the picture of the Mondial ISC test desk, top right of the left hand panel."

The End
Relocation of telephone exchanges to meet the changing needs of the business is not a new idea. In the Eighties, the crossbar switches were mechanically wearing out, rates in London were high, and the advent of digital technology allowed manual boards to be remote from the switches that they controlled. Peter Walker recalls... "I was involved in the Wood Street sale project. It raised £54M so was too good to pass over." Sources state that Wood Street was due to close by 1990.

The International Control Centres (ICCs)


An overseas (International) exchange opened in the Monarch ATE building on 24th November 1947. This was to provide relief for the growing number of radio circuits. The switchboards operated via the Radio Telephony Terminal (RTT) with equipments being housed in Faraday Building (Blackfriars) and Brent Building (Hendon).

The boards were 4 feet 81/2 inches high, sleeve control type with 105 positions:

84 main operating positions, 21 enquiry, record and obs. positions
Wood Street  1948, home to Monarch ATE
"When we moved into the top floor of Wood Street from Faraday in 1947 it was the only building still standing amongst all the bomb damage. "

If you compare this photo with the one of Wood Street ISC (above) you can see how the space on the corner was filled.

Photo: Monarch TE circa 1948.
Barbara Ball (Nee Parkinson) writes...

"When we moved into Wood Street from Faraday in 1947 it was the only building still standing amongst all the bomb damage. The Overseas Exchange was all very new and all communication was by radio. We shared the building and facilities with Monarch Exchange and we certainly did not have the luxury of a bar in the canteen. "

[See later comments about the bar in Wood Street.]

"I remember the divisional Supervisor sitting in the middle "listening in"; we used to make excuses to walk behind her to see who it was, but she always had a piece of paper over the jack so we couldn't see. The whole of International as we then became, moved to Wren House in the early 60s and I spent many happy years with them till I left to get married in 1967."

Although the International section moved out, Wood Street carried on...

Wood Street 1 [LWICC/1]

ICC (1962)

By 1962, the 117 positions of the International exchange (in the Monarch Building - see above) were reduced to just 96 to be converted for continental working.

Thus on 25th August 1962, The London Continental Control Centre opened in Wood Street with an initial 55 positions. Wood Street handled all overflow calls from Faraday for countries using English as the main operating language. [Subscribers in London dialled 105.] Traffic to countries requiring linguist (mainly French speaking) operators was retained at Faraday.

Into the Eighties
Into the Eighties
"In the early 1980s an international phone call sounded quite different from today. Even if the subs making the call weren't paying, calling overseas was still quite an event for a lot of people, so on hearing: 'This is the United Kingdom calling. Will you accept...' we would hear squeals of delight...!".

Photo: Wood Street 1 1986
Wood Street 2

ICC (1971)

In 1971 another ICC opened in the new extension which formed part of the ITSC. Wood Street 2 was equipped with 114 positions. It used crossbar switches for the bypass switching and a peculiar form of multi-level DC signalling (confusingly called DCC) into the ISC.

The remaining ICC in the old building was officially renamed Wood Street 1, but generally continued to be known simply as Wood Street. Wood 2 (later to become Wood SPC) was on the 4th floor of the new wing (closest in the photograph) and overlooked London Wall. The Wood Street canteen was above on the 5th floor, also overlooking London Wall.

Wood SPC (circa 1985)

[More later]


"Once the sleeve control units had gone, we never got as much fun. What we did have was Caller Line Indicator (CLI) which meant if the chargeable number did not match the one the caller gave we could always recall. We also thought we'd lost the ISOCC tickets until a Senior Operator (SO) or Operator Services Supervisor (OSS) had to do the rejects from the INSIST list onto ISOCC tickets."

"INSIST appeared in the form of a huge printout of call details that didn’t compute. In the AXE-OPS SPCs, if anyone did a COD99 or a DUR input, it appeared in the INSIST days later. If we input the B-No (distant end number) in such a way that it didn’t read correctly it also appeared in INSIST. Needless to say, INSIST got nicknamed INCEST, though the person who ended up re-entering the details on ISOCC tickets, occasionally myself, did not look forward to doing that job. Some had 0 (zero) values on both A-No and B-No sides, so heaven knows where those calls came from nor went to."

In April 1988, Telecom Today reported :

"A new international operator centre is to open in Grimsby, Humberside. It will take over the work of London's Wood Street centre, which is due to close in 1990. Staff currently working at Wood Street will be offered relocation to Grimsby on compulsory transfer terms."

Wood Street Rings The World" by E T C Harris from Post Office Telecommunications Journal Autumn 1972.
The Wood Street (London) ITSC by G J Beckett.
Thanks to memories from several Wood Street operators and Youngleavers.
Design, images and text compiled by © Light-Straw. Page last updated 16th February 2013. Checked May 2021.

All logos and trade marks are the property of their respective owners and are used on the Light Straw site(s) for review only. Students and researchers are recommended to make their own independent enquiries as to the accuracy of the information contained therein.