[HN Gopher] Telephone Exchanges in the UK
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Telephone Exchanges in the UK
Author : petecooper
Score : 162 points
Date : 2025-06-15 19:33 UTC (1 days ago)
(HTM) web link (telephone-exchanges.org.uk)
(TXT) w3m dump (telephone-exchanges.org.uk)
| biofox wrote:
| This is an impressive feat of cataloguing!
|
| Considering the telecom system is at the bedrock of almost all
| modern technologies, it really doesn't get enough love or
| attention in the public mind.
|
| The dull derelict-looking, and often graffitied, buildings that
| house the system doesn't reflect just how cool the infrastructure
| is.
| rwmj wrote:
| My physics teacher in the 1980s (sadly RIP a few years ago[1])
| told me that the location of telephone exchanges was a UK state
| secret. The theory was that the Russians would nuke them
| destroying the country's ability to communicate, but as their
| location was a secret that outcome could be prevented. 40+
| years on, I wonder if any of that was actually true?
|
| [1] https://johnchess.blogspot.com/2019/11/david-
| welch-1945-2019...
| toyg wrote:
| The dullness is eerily consistent. Even in the age of
| privatisation, when everything is a brand, these buildings
| are devoid of markings. So it might well be true, we just
| stopped worrying about it once the cold war was officially
| over (once we realized the Russians already knew everything
| they needed anyway).
| edent wrote:
| Sort of, yes. https://en.wikipedia.org/wiki/BT_Tower#Secrecy
| biofox wrote:
| Two more examples of exchanges that were kept secret:
|
| https://en.wikipedia.org/wiki/Anchor_telephone_exchange
|
| https://en.wikipedia.org/wiki/Guardian_telephone_exchange
| lxgr wrote:
| Wait, what? What else were people supposed to assume about
| the purpose of a huge tower with very noticeable horn
| antennas (widely used for long-distance phone calls over
| line-of-sight microwave at the time)?
| razakel wrote:
| It also had a restaurant open to the public.
| ta1243 wrote:
| The one place in London you can't see it
| snthd wrote:
| >As our [1978] trial started, witness after witness from
| security sites tried to claim that openly published
| information was in fact secret. In a typical interchange, one
| Sigint unit chief was shown a road sign outside his base:
|
| > Q: Is that the name of your unit?
|
| > A: I cannot answer that question, that is a secret.
|
| > Q: Is that the board which passers-by on the main road see
| outside your unit's base?
|
| > A: Yes.
|
| > Q: Read it out to the jury, please.
|
| > A: I cannot do that. It is a secret.
|
| >Official panic set in. The foreign secretary who GCHQ had
| bullied into having us accused of spying wrote that "almost
| any accommodation is to be preferred" to allowing our trial
| to continue. A Ministry of Defense report in September 1978,
| now released, disclosed that the "prosecuting counsel has
| come to the view that there have been so many published
| references to the information Campbell has acquired and the
| conclusions he has drawn from it that the chances of success
| with [the collection charge] are not good."
|
| >My lawyer overheard the exasperated prosecutor saying that
| he would allow the government to continue with the espionage
| charge against me "over [his] dead body." The judge, a no-
| nonsense Welsh lawyer, was also fed up with the secrecy
| pantomime. He demanded the government scrap the espionage
| charges. They did.
|
| GCHQ and Me, My Life Unmasking British Eavesdroppers --
| Duncan Campbell
|
| https://theintercept.com/2015/08/03/life-unmasking-
| british-e...
| JdeBP wrote:
| In hindsight, that does seem a little ridiculous; yet it was
| indeed the thinking. One could _see_ where the exchanges were
| by simple dint of visiting a place. Soviet spies would just
| have had to walk around a bit.
|
| Of course, nuclear weapons wouldn't even have had to
| specifically target exchanges in order to disrupt electronic
| communications as they already were by the 1980s.
|
| It was amusing to learn a decade ago that the U.S.S.R.
| military had far more complete maps of many parts of the U.K.
| than Ordnance Survey published. Apparently down to Soviet
| spies just walking around a bit, playing tourist.
| ajb wrote:
| _U.S.S.R. military had far more complete maps of many parts
| of the U.K. than Ordnance Survey published._
|
| Although amusing, note that its _than the Ordnance Survey
| published_. I.E. they had the data, it was just classified.
| Also, it 's fairly clear that the Soviet maps were mostly
| derived from OS maps. Looking at my street, for example,
| they have it in a pre-WWII configuration which they could
| only have got by starting from a rather old OS map. So they
| clearly only checked for differences in areas they thought
| important, such as government or military areas - they
| didn't have people mapping the whole UK. Still it's
| probably true that one can get more information about
| certain areas in these Soviet maps than in extant OS maps.
| logifail wrote:
| > the location of telephone exchanges was a UK state secret
|
| I found myself wondering whether the locations of electricty
| substations powering critical infrastructure might count as
| "secret", for instance the three[0] substations that power
| Heathrow Airport.
|
| Obviously one of them isn't secret any more more, having gone
| up in flames rather spectacularly on 21 March 2025.
|
| [0] "Heathrow relies on three electricity substations"
| https://www.bbc.com/news/articles/c6283577llqo
| thorin wrote:
| It wasn't very secret, at least for local exchanges as I went
| into many in the north-east of England with my dad as a kid.
| ipdashc wrote:
| In a similar vein, but for the US: https://www.co-buildings.com/
| (And a shoutout to https://long-lines.com/)
| tdeck wrote:
| If anyone is interested in telephone exchange technology at all,
| I highly recommend checking out the Connections Museum in
| Seattle. They have multiple eras of electromechanical switching
| equipment up and running, and a huge collection of cool old
| phones, teletypes and payphones. They also have a great YouTube
| channel with very knowledgeable people.
|
| https://www.telcomhistory.org/ConnectionsSeattle.html
|
| https://m.youtube.com/@ConnectionsMuseum
|
| I feel like they're not well known and there's no place like it!
| evolextra wrote:
| I know one guy who make something cool with old Telephone and
| electronic stuff https://this-museum-is-not-obsolete.com/
| g-mork wrote:
| Don't miss https://www.youtube.com/watch?v=kfOzyIib7wU for some
| young folk urban exploring what turns out to be a still active
| exchange, full of ancient and modern tech
| tobinfekkes wrote:
| Another excellent museum is the Kodiak Military History Museum
| at Fort Abercrombie, on Kodiak Island, Alaska.
|
| It has some old working telephone and teletype systems. You can
| watch the physical switching equipment do its magic. It is
| truly awesome. The raw speed and accuracy of the mechanical
| systems is almost unbelievable.
| jonatron wrote:
| I visited an exchange back in 2009, when Local loop unbundling
| (LLU) on ADSL was big, and fibre was limited to large business
| and datacentres. The huge generator was probably more interesting
| than the racks of concentrators. I'm not sure how much battery
| back-up power time the new PON systems have, I assume less than a
| generator backed system.
| danw1979 wrote:
| Was this the BT demo exchange somewhere in Essex ? Bishop
| Stortford maybe ?
|
| I did that tour around the same time and it was fascinating !
| right in the middle of the 21CN (ethernet core network)
| transition.
| jonatron wrote:
| No, it was just a normal BT exchange in Suffolk
| ricardo81 wrote:
| Our old countries (and their tech) building on top of old.
|
| Developing countries have less of a hassle with implementing
| something based on state of the art.
|
| Lots of hassles with getting new phone lines, new power lines et
| al in the UK based on old agreements and a nationalised
| infrastructure. Please stop digging up roads and everything for
| arbitrary telecoms companies based on some deregulation, some
| collaboration please :-)
| f4c39012 wrote:
| someone from the local gas company told me that the reason the
| utilites don't work together is that they can't because of
| rules - electric and gas need to be kept separate for safety,
| and the surrounding soil means water leaks can be absorbed away
| from other utilities' pipework. I didn't dig any deeper
| kimixa wrote:
| I feel there's a generation of Brits burned the wave of
| random telecoms companies digging up major roads for years
| for cable, only for the results to be pretty much useless by
| the time it's done as ADSL and existing POTS lines could do
| pretty much the same thing without any more digging.
|
| The words "Diamond Cable" still fill me with dread to this
| day. They dug up half our village to then offer no service.
| Affric wrote:
| The roadworks during my youth were endless. It was
| maddening. Never occurred to me that it could have all been
| telcos.
| JdeBP wrote:
| I know someone who is still waiting for City Fibre, who dug
| up xyr road last year, to get around to actually offering a
| service.
| rcxdude wrote:
| City Fibre has worked alright around where I live. It was
| also about a year or so after most of the digging (now a
| few years ago), but it's been nice to have actual fibre
| internet (through a different ISP, since they just do the
| infrastructure).
| danw1979 wrote:
| A local fibre co here in York dug a cable to all the way
| my parent's farm house, about 250m outside the nearest
| village (and probably even further into the village to
| reach the PCP), then left the cable coiled up on the
| outside of their property and haven't done anything
| further with it in over a year.
|
| I've heard other similar stories from friends in the city
| too.
|
| It's almost like there's money for the infrastructure but
| not for the staff required to actually run it as a
| service...
| dazzawazza wrote:
| Where as in London, where there is at least one house
| every 8 meters, they were in and out of my street in two
| days and now we have constant door to door sales people
| offering deals.
|
| Smells like they "installed" fibre in York to meet a
| contract/regulation but they really focus on Urban
| density. Makes sense for them but not for the rest of us.
| matt-p wrote:
| Like most things that's half true.
|
| It's true you don't want a telecom worker laying a gas pipe,
| however you can coordinate this stuff if you want to.
| Typically the deepest utility works first then backfills just
| to the level of the next utility and so forth. However timing
| is critical, the second utility must be ready to work as soon
| as the first is done and so on.
|
| The biggest reasons they don't is mostly (in this order)
|
| -They can't time their work to be at the same time as 3 other
| utilities.
|
| -They can't work out cost and liability sharing, if the last
| utility to work does the reinstatement and takes liability
| for it then the telecom company will always pay while
| electric typically won't pay anything as it's in the middle.
| The legal demarcation between utilities is also much less
| clearly defined.
|
| -Contractors typically do all work, not actual utilities and
| it's in their best interests to dig the road up five times
| (one for each utility) rather than just once. The same goes
| for everyone else who gets paid when the road is opened;
| including, often, the local government (for permits).
| jansper39 wrote:
| No thank you, my Cityfibre connection is 2/3 of the cost of a
| BT hosted one and is 150Mb up and down, instead of BT's
| asynchronous offering. Installed in a couple of days of
| ordering too.
| unwind wrote:
| You meant *asymmetric offering, right?
| TorKlingberg wrote:
| Interestingly, Cityfibre often reuse the old telephone poles.
| It means you can get fibre to the home with no digging
| required. Yay old tech?
| _joel wrote:
| You can go and play with an old branch exchange, with all the
| whistles and er, bells at "This Museum is (not) Obsolete". Run by
| Sam from Look Mum No Computer. If you're ever near Ramsgate in
| the UK.
|
| https://this-museum-is-not-obsolete.com/
| linker3000 wrote:
| See also in West Sussex:
|
| https://www.amberleymuseum.co.uk/explore/explore-communicati...
|
| https://www.amberleymuseum.co.uk/explore/explore-communicati...
| cph123 wrote:
| He also has a fascinating YouTube channel, I'm a big fan. Lots
| of old musical equipment and experiments in addition to
| telephony.
| heraldgeezer wrote:
| Really, its own internet system before the internet. Massive load
| of calls. The routing has to be correct. I never understood it
| before working in telecom, but phones numbers are unique... for
| routing, like IP-addresses. And it could never go "down". In the
| 80s it was all digial too (Ericsson switches) and had to be real-
| time.
| psychotaurusaqu wrote:
| Combination of Ericsson and GEC/Plessey/BT "System X" (see
| https://en.wikipedia.org/wiki/System_X_(telephony)). Erisson
| AXE10 was known as "System Y" in the UK and a hedge against
| buying exclusively System X equipment.
| gjvc wrote:
| see also
| http://www.samhallas.co.uk/repository/po_docs/system_x.pdf
| and http://www.samhallas.co.uk/repository/journals/BTEJ/BTEJ%
| 20V...
|
| and this
|
| https://www.academia.edu/39809466/System_X_The_history_of_th.
| ..
|
| by http://www.kingdom-technology.co.uk/malcolmhamer.php
| merlynkline wrote:
| Before modern digital electronics, telephone numbers were
| literal routes - when the turned dial on your phone ran back to
| zero, a corresponding 10-pole motorised rotary switch at the
| exchange turned and connected you to one of 10 lines. This
| connected you to another such rotary switch for the next digit,
| until eventually you were connected to the final destination.
| The ingenious Strowger exchange.
| lxgr wrote:
| Invented by a paranoid undertaker out of business interest,
| apparently:
|
| "Strowger, an undertaker, was motivated to invent an
| automatic telephone exchange after becoming convinced that
| the manual telephone exchange operators were deliberately
| interfering with his calls, leading to loss of business."
|
| I wonder if the phone company was actually out to get him!
| pests wrote:
| I've heard this story before and it included the detail
| that his competitor's wife worked as an operator at the
| exchange, and his worry was she would direct calls for an
| undertaker to her husband instead of himself.
| userbinator wrote:
| Also, every phone had its own physical circuit to the
| exchange, leading to things like this:
| https://i.redd.it/ugvoc90k4q5a1.jpg
| heraldgeezer wrote:
| Crazy. There is also the https://en.wikipedia.org/wiki/Old_
| Stockholm_telephone_tower#...
| steelegbr wrote:
| Generally yes and even today, if you've got a twisted pair,
| it's that down to the exchange. Though party lines were
| also a thing a very long time ago.
|
| There were also specialist circuits (e.g. EPS) where you
| had a physical line from end to end (with a couple of amps
| along the way on longer runs).
| redjet wrote:
| That mention of EPS takes me back, we used to use it all
| over the place to form basic hub-and-spoke networks in
| areas where we had lots of small sites that would all
| connect to a single exchange. It would generally bounce
| along at 2Mbps which wasn't bad in those days.
|
| We also had some large campus type sites where we would
| sometimes implement EPS to do LAN extension over the
| onsite twisted pair as it was cheaper than installing
| fibre and just about fast enough.
| miki123211 wrote:
| And when there was a bug in that complex and vast routing
| system somewhere, it was completely unfixable. Not without
| million-dollar hardware replacements at least.
|
| It's really surprising to me how little uptake 2600
| ultimately ended up having.
| ipdashc wrote:
| > Really, its own internet system before the internet. ... for
| routing, like IP-addresses.
|
| There's a great video from Connections Museum (mentioned
| further up the thread) where they're going through the
| operation of, I want to say, one of those crossbar switches?
| And they start using terminology like "routing table",
| "longest-prefix matching", and "default route", which all
| sounds well and good, until you realize they're talking about
| systems that existed decades before the Internet or even
| ARPANET, all electromechanical... Dope stuff. Cool to see how
| things rhyme even as they change.
| backendEngineer wrote:
| and it's gone... 429 :D
| bravesoul2 wrote:
| Distributed curiousity attack
| dboreham wrote:
| Interesting to see Kinghorn in the database (01592-89) because I
| toured the exchange as a child sometime in the late 1970s before
| it was brought into service (my Dad knew a bloke who worked for
| GEC). iirc it was a TXE4 system then, or at least of that
| generation. Building in a very poor state of repair now. Probably
| hasn't been painted since 1979!
| arethuza wrote:
| I walked past there the other day (on the Fife coastal path)
| and wondered what the shabby building was - I had assumed it
| was an abandoned light industrial unit.
| bravesoul2 wrote:
| I recall there was a voting system by BT circa 2002 to get your
| local exchange upgraded to "broadband" (i.e. not just 56k dialup)
| if it wasn't already.
| GJim wrote:
| No.
|
| It certainly wasn't a voting system. Rather, it was a decent
| enough system used to help gauge demand in a given area.
| (Unsurprisingly, there was a lot of demand for ADSL in
| university towns, and much less in retirement-town-by-the-sea).
| bravesoul2 wrote:
| Voting may be the wrong word but I think if you lobby your
| local area to submit their interest you'd have a good chance
| of getting it activated. There was a threshold and a tracker
| on the website.
| penguin_booze wrote:
| Now, where are the STD jokes?
| ThePowerOfFuet wrote:
| The site won't let me past the initial verification page in
| either Firefox or Vanadium.
|
| Is their content really so sensitive that it must be "protected"
| to such a degree?
| domh wrote:
| Working fine with Firefox on Android here. Desktop or mobile?
| oniony wrote:
| The Avoncroft museum of buildings in Bromsgrove, near Birmingham,
| UK, is worth a visit. They have a bunch of old telephone boxes
| all working and hooked up to an exchange they have on site. I
| spent like an hour talking to the guy in there about it all,
| pretty fascinating.
|
| https://avoncroft.org.uk/avoncrofts-work/special-collections
| ehecatl42 wrote:
| If you find yourself in that part of the world, there's also a
| carpet museum in Kidderminster, and the Black Country Museum in
| Dudley. A little bit further north and then there are a slew of
| industrial museums in Ironbridge.
| Neil44 wrote:
| I was going to post this, I had a fab time in that little room
| with all the click-clacking gear.
| thorin wrote:
| My dad worked at BT and used to take me to different exchanges at
| the weekend normally on Saturday mornings. I guess he claimed a
| day in lieu for working a couple of hours and then we went for
| lunch or pottered around the shops. In there were all sorts of
| interesting things. Piles of discarded electronics of various
| eras. Several computers and terminals for connecting to mainframe
| systems. I remember a Sinclair QL and Amstrad PCWs I think. He
| would let me play around with the terminals, no idea what OS was
| on there maybe VAX or VMS, use the printers and Microdrives. I
| was really interested in all that stuff as a kid but didn't
| really have anyone to learn from as my dad was more of a lineman,
| having started in the Royal Signals. Fun times!
| voidUpdate wrote:
| I used to live pretty much opposite the village exchange. It was
| just a very boring and nondescript little building, backed up by
| the picture on that website. I bet it was much more interesting
| inside though
| dugmartin wrote:
| My dad was a telephone engineer/manager with GTE in the US. As a
| kid in the mid 1970s he used to take me with him to the local
| exchange building to deliver donuts to the guys on duty (he was
| that kind of boss). The security was interesting - there was a
| tube built into the masonry with a 90 degree angle that had a
| mirror. He would pick up the phone on the outside wall and say
| his name and an identifying number and then the door would buzz
| open. The building was a few stories tall and had no windows,
| which I think was a Cold War thing.
|
| We would deliver the donuts to the break room which usually had
| at least one guy smoking in it (it was the '70s). A couple of
| times we went into the switching room which still had rotary dial
| switches clacking away as people dialed in numbers. There was an
| overwhelming smell of ozone in the room. It was all very cool to
| 5 year old me.
| mojo74 wrote:
| Shout out to Milton Keynes Museum for their archive of handsets
| old and new as well as interactive examples of telephone
| exchanges:
|
| https://miltonkeynesmuseum.org.uk/collections/view-our-colle...
| bdsa wrote:
| My dad (who worked for BT in various positions) claims he was
| involved with the decision to move the exchange in our/their
| village from one end to the other. Coincidentally, closer to the
| end in which we lived, which I gather would have a non-trivial
| impact on our internet speed.
|
| I think this probably coincides with the time period we got ISDN,
| very early, and I was amazed by the concept of _always connected_
| internet. I can still vividly remember watching GoZilla download
| a game demo at 7kb/s, stunned and excited.
| bloomingeek wrote:
| Although I never went into one of these buildings, in the early
| 80's I was a sub-contractor burying cable for SWB. I was always
| amazed at all the property they controlled. I had access to all
| their construction yards, which were spread out all over the
| city, some of them in the suburbs. Protecting these yards from
| theft was always a nightmare for them.
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