[HN Gopher] Old Stockholm Telephone Tower
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Old Stockholm Telephone Tower
Author : ZeljkoS
Score : 145 points
Date : 2025-10-02 07:12 UTC (2 days ago)
(HTM) web link (en.wikipedia.org)
(TXT) w3m dump (en.wikipedia.org)
| ZeljkoS wrote:
| It is speculated that this was an inspiration for the Citadel in
| Half-Life: Alyx VR game:
|
| https://www.reddit.com/r/HalfLife/comments/e809fn/cant_help_...
| sans_souse wrote:
| This is actually amazing
| thakoppno wrote:
| There are more telecommunication lines now than ever. We've just
| gotten really good at organizing them?
| kibwen wrote:
| We've gotten really good at multiplexing lots of connections
| over a single line.
| kikokikokiko wrote:
| I believe the concept of multiplexing made the tower obsolete,
| orher than the subterranean cables of course.
| ntoskrnl_exe wrote:
| I'm not sure that plain old telephone service allowed
| multiplexing, so it was probably just the latter
| solid_fuel wrote:
| It did to an extent, they built the old copper network in
| tiers. I don't know the exact numbers and I'm sure they
| varied by area, but the general idea was - your home phone
| would connect to a local exchange, which served just dozens
| of local homes, and that exchange would connect to a bigger
| exchange somewhere higher up the network over a bundle of
| circuits. And that architecture repeated for a few layers.
|
| But it wasn't 1:1, so you would have lets say 100 homes
| connected to a local exchange, and that local exchange
| would have say 20 lines to the next exchange in the
| network. That placed limits on the amount of concurrent
| connections you could have from one area - if 21 homes all
| tried to call people in the next city over, at least one of
| them would get a signal that all circuits are full and they
| would have to try again later. It drastically reduced the
| amount of lines you need between local exchanges though.
| cpach wrote:
| Interesting!
|
| I guess it helped that phone calls were quite expensive,
| so people generally made very short calls. I haven't
| really thought about this before but one of the main
| reasons for the pricing system could have been the facts
| that you mentioned.
|
| In Sweden, the pricing system was tiered. Same area code
| (roughly: same municipality) = lowest rate. Neighbouring
| area codes = higher rate. Outside of that = highest rate.
| The rate was halved after 6pm. A reason for lowering the
| rates in the evening might have been that there were far
| less business users calling after 6pm.
|
| One of the reasons I remember the pricing system is that
| my parents would not be happy if I dialed in to a modem
| pool before 6pm :)
|
| Before I was born, the telephone company in Sweden
| (Televerket, later Telia) started to upgrade their system
| to use digital telephone exchanges (AXE). But there were
| of course still some kind of hard limit for how many
| concurrent calls they could handle, so I guess that's why
| they kept the pricing system for a while.
|
| This is partly speculation on my part, so feel free to
| correct me if I'm wrong.
| solid_fuel wrote:
| Yep, that's right. The long distance trunks were a more
| limited resource so the telcos charged more per minute to
| use them. After digital exchanges came around it was less
| of a factor, but I think the pricing structure stuck
| around for a while.
| greenbit wrote:
| You'd think that at least initially, individual towns
| would stand up fully connected (albeit small) but
| isolated networks. That before very long, the idea of
| connecting one town to the next would occur, and it would
| be realized that you only need a relatively small number
| of "long distance" lines, connected between the existing
| switchboards. At which point, if you were wiring up a
| city, you'd follow that pattern; tiered layers, as you
| say. It stands to reason then, that Stockholm's system
| must have started very early, and had absolutely
| explosive growth, to get to a situation like that tower.
| varjag wrote:
| It absolutely did, in 3kHz bands. That's how you could also
| sometimes hear someone else talking.
| cgio wrote:
| Single point of failure?
| viraptor wrote:
| A lot of old telephony systems were full of SPoFs.
| oofbey wrote:
| A core design principle of the Internet was the ability to
| automatically route around damage. The requirement came from
| a desire to be robust against nuclear attack. Very few 20th
| century networking systems could do this. Star topology or
| ring topology all had intrinsic SPoF.
| bombcar wrote:
| That is exactly how I envision the clacks based on Pratchett's
| descriptions. Maybe without _exactly_ that many wires ...
| atombender wrote:
| But clacks are optical telegraphs [1]; they communicate by
| semaphores, not wires.
|
| [1] https://en.wikipedia.org/wiki/Optical_telegraph
| shantara wrote:
| For me, this picture is more of China Mieville than Pratchett.
| dmd wrote:
| Wouldn't the number of wires be.... zero? The clacks are
| optical. They're semaphore.
| ValtteriL wrote:
| NK logo and all
| iberator wrote:
| And that's why we invented multiplexing and even better: store
| and forward packets.
| dredmorbius wrote:
| More specifically, packet-based rather than switched telecoms.
|
| Using a switch, each connection is a literal physical circuit.
| Multiplexing allows multiple _circuits_ per phone line (through
| frequency separation at the carrier-frequency level), and much
| early telephony research involved increasing the multiplexing
| capacity and consequent issues.
|
| With packet-switched networks, the only circuits are the
| interconnects between routers, and _each individual data
| packet_ can take a different route. Subject to quality of
| service / service level agreements (QoS / SLA), it's possible
| to support far more distinct individual connections over
| packet-switched networks, though there still remains a maximum
| total bandwidth. For time-sensitive modalities (e.g., realtime
| voice or video), excess traffic leads to congestion and
| buffering, distortion, or interference, so limits remain. But
| they're far more generous than with circuit-based networks.
|
| Put another way, packets give a greater assurance of
| establishing a link between any two nodes, whilst circuits give
| a greater assurance of a minimum bandwidth floor between those
| nodes. If you _can_ get a connection, circuit-based line
| quality is often (though not always) superior, in terms of
| consistency, clarity, and low latency.
| ssl-3 wrote:
| That doesn't necessarily line up with my understanding of
| reality.
|
| In the US, a PRI can handle up to exactly 23 concurrent,
| native g.711u phone calls. That's it's capacity: No more, and
| no less. It's always 23, with each concurrent call using
| exactly 64kbps of symmetric bandwidth....just because that's
| the number of B channels provided.
|
| But if we take that same PRI and make it do IP packets
| instead using MLPPP, then our capacity is actually reduced.
| By adding the magic of packet switching, we also add
| overhead. And with that added overhead, we can only get only
| get ~19 g.711u calls through that same circuit.
|
| (Now, sure: In a bigger picture, that PRI may be better
| utilized as an IP pipeline than as a dedicated telephony
| circuit. It's certainly more flexible that way.
|
| But packetization is not something that automatically
| improves capacity. It often does the opposite.)
| designerarvid wrote:
| Not only was the tower demolished, some 700 buildings in that
| central area were in efforts to modernise the city.
|
| https://en.wikipedia.org/wiki/Redevelopment_of_Norrmalm?wpro...
| cpach wrote:
| What kind of solutions were employed in other cities? Does anyone
| know? Cities like London and New York etc must have had much more
| telephone lines.
| tazjin wrote:
| At this early time (this is not long after the invention of the
| phone itself) - none, really. Stockholm had a much higher
| number of telephones per home, but not very long after this
| operators put the cables underground and that was that.
| greenbit wrote:
| Does this mean that probably somewhere below that tower, there
| were operator stations that would have allowed any of the 5500
| lines to connect to any of the other lines? How many simultaneous
| calls would that even be? Correct me if I borked this, but
| 5500!/(2^(5500/2)), perhaps?
|
| It seems plausible that if the phone had only just been invented,
| you'd initially set up small systems that would in fact allow any
| line to connect to any line. That'd be fine for maybe even a few
| dozen lines. But as the image shows, that doesn't scale too well.
| dredmorbius wrote:
| The total number of _connections_ would all but certainly be
| far greater than the maximum number of simultaneous _calls_
| which could be supported.
|
| Under PSTN, public-switched telephone networks, a not-
| infrequent occurrence, especially when calling long-distance,
| was to get a message "all circuits are busy". When each call
| was literally a circuit, and the "switch" (the central
| telephone exchange) made and broke those circuits as calls
| began and ended, my understanding (not my area of expertise,
| but one of some interest) is that this meant that _all
| available interchange connections were occupied_. For long-
| distance, this was typically far lower than for local calls
| (most phone traffic is local), and for international calls,
| lower still. The first transatlantic telephone cable could
| support only _36_ simultaneous calls, in 1956. Calls were
| short, expensive, and all but exclusively for business and
| government subscribers.
|
| <https://hamhistory.org/first-transatlantic-telephone-cable/>
|
| I'd expect that the Stockholm exchange probably supported a few
| hundred simultaneous calls, probably a few (a dozen or so
| perhaps) per operator, who had to physically connect each call.
| analog31 wrote:
| Indeed, I'm old enough to remember "all circuits are busy."
| lanna wrote:
| If you have n nodes, each one needs to connect to n-1 other
| nodes. But the connection from A to B is the same as the one
| from B to A. Therefore, there are n(n-1)/2 total connections.
| Isamu wrote:
| Comments mention multiplexing and that's not wrong but the real
| reason for the vast number of wires is amplifiers, or rather the
| lack of practical ones at the time. You had to transmit at high
| enough power to overcome losses and still be able to hear at the
| destination.
|
| Each wire carries just one signal at a power that would easily
| interfere with others, they needed relatively thick wires
| separated from each other. You see pictures of poles with lots of
| cross bars carrying lots of wires in this period.
|
| Once amplification was practical they could use the thin
| telephone wires bundled together in a cable, each wire carrying a
| much fainter signal that can be easily amplified as needed.
|
| Amplification existed but it took the vacuum tube to get it
| affordable and reliable for each circuit to have its own
| amplification.
| Waraqa wrote:
| Does that mean the quality of the voice calls in that era was
| better than later systems? Since it's logical to have loss of
| quality when a weak signal is amplified.
| munchlax wrote:
| I suspect the quality was poor in the 19th century due to not
| yet knowing how to make good receivers and mouthpieces.
| Isamu wrote:
| Right, quality was poor and the transmitter and receiver
| were part of the problem. They experimented with different
| methods, but part of the problem was that without
| amplification they needed a transmitter that worked at the
| full voltage necessary to travel the full distance.
| jcrawfordor wrote:
| When the tower was constructed in 1887, multiplexing technology
| was probably not available (I'm not so sure of the timeline in
| Europe). By 1913 it likely would have come into use. However,
| multiplexing really isn't a factor here, as the tower seems to
| have been built to serve local loops. Since these loops go to
| subscriber telephone sets, there's no option for multiplexing
| without expensive and maintenance-intensive equipment at customer
| premises. Multiplexing of local loops is called "pair gain" and
| wouldn't be developed until later, and it was never really that
| popular in most phone systems. Outside of suburban areas, it's
| typical that each copper pair runs directly to the exchange.
| Historically, and today, there is rarely any active equipment (or
| since the 1950s or so even passive conditioning) on local loops,
| they're just wires from the exchange to the phone.
|
| As for why you didn't see similar constructions in other cities,
| this was definitely an unusually large telephone office for the
| time. In the US, a city exchange of the late 20th century would
| usually have just hundreds of lines, many of them multi-party.
| Telephone companies scaled up by building more exchanges, rather
| than a single very large one. When they got into these kinds of
| subscriber numbers at an exchange, the F1/F2 cable scheme was in
| use to avoid this kind of wiring. It does seem to be the case
| that telephone adoption was unusually rapid in Sweden, I find one
| (poorly sourced) claim that there were some 4,800 telephone
| subscribers in Stockholm in 1886 which would very likely make it
| the most telephone-rich city in the world. The situation of the
| tower seems to have developed in part because its builder,
| Allmanna, was consolidating the Stockholm telephone market
| through acquisitions and made a decision to centralize the many
| acquired customers onto on exchange.
|
| What I'm a little confused about here is the lack of cables. The
| other big reason you didn't see constructions like this in the
| US, even in places like New York City, is because subscriber
| loops were quickly moved into lead-sheathed, paper-insulated
| multi-pair cables. These could contain hundreds of pairs. Cables
| were pretty much reaching maturity when this tower was built. I
| am curious as to the reason that multi-pair cables were not
| adopted more quickly in Stockholm, but it may be as simple as the
| considerable investment in this tower making open wire the
| preferred option for its short lifespan. In any case, the common
| claim that _underground_ cables obsoleted the tower rings hollow
| to me, or at least misses an important detail, as aboveground
| cables were already in use in the 1880s. I suspect that
| modernization to cables was just deferred in Stockholm until it
| happened to also make sense to move to duct or pipe systems. In
| the US, it was more common that telephone exchanges switched to
| overhead (aerial) cable to manage exactly the wire sprawl issue
| that this tower exemplifies, and then only later (if ever)
| started to bury cables.
|
| This article has more photos of the tower, but unfortunately not
| much more technical history:
| https://rarehistoricalphotos.com/the-stockholm-telephone-tow...
|
| And this includes some photos of other parts of the Stockholm
| telephone network. The tower was not the only impressive
| construction required to manage this many open-wire pairs:
| https://thehistoryinsider.com/when-the-sky-over-stockholm-wa...
| finaard wrote:
| > As for why you didn't see similar constructions in other
| cities, this was definitely an unusually large telephone office
| for the time
|
| For some perspective here - it took until the mid-80s for most
| of Germany to be connected to a phone line. That is, the 1980s.
|
| I recently talked about that with my father after I found a
| postcard from one of my uncles from the early 80s confirming
| meeting and dinner plans. While I remember them always having a
| phone they were one of the households only connected in the mid
| 80s - which in retrospect explains some of the things I've
| found odd about them when talking to them by phone. It was a
| new thing for them.
|
| (My parents got connected early on - my mother used to work for
| the post office in the phone exchange, and one of the perks of
| the job was priority for getting a phone line. Which also
| explained why we had an old grey phone, while pretty much all
| my friends had a relatively modern - for the time - one: they
| all only somewhat recently got phones)
| speerer wrote:
| I just wanted to say that after the first paragraph, I wondered
| who this comment was written by, and then I realised I knew the
| answer already. There was no need for me to even check.
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