The Strowger Step By Step Telephone Exchange

This is an alternative edit of this video :-
• STROWGER Telephone Exc...
Richard talking more about the setup :-
• Strowger Step By Step ...
focusing on Richard who lovingly built up this Strowger step by step demonstration setup, I first spoke to Richard after finding him selling some exchange items online, after a conversation it turned out he was planning on dismantling his strowger exchange setup, but after a chat it made sense to keep this setup together and functioning!
Museum opening very soon www.museumofev...
if you'd Support these videos and subsequent museum
/ lookmumnocomputer
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[@stevewatkins1221]

This is a great explanation and demo. When I did my apprenticeship we learnt Strowger, sadly digital SystemX came along so never got to work on one. Was lucky enough to see a few working in British Telecom buildings. To hear these sounds of the selectors stepping through is truly magic. Multiple that sound by 1000 and up the volume, and you get an idea of the sheer noise of a telephone exchange during busy hour. Today one computer no bigger than a the final selector can handle 1 million calls. Only the sound of the fan to keep the computer cool. No sound, and no smell of oil. It's just not the same.... thanks for making this video

[@Christophersanchez1326]

I remember felling and hearing all of those switches making the calls within a room with thousands of those machines. Thanks dad. Rip.😢

[@LostInTech3D]

it's hilarious how a spurned undertaker becomes charles babbage overnight.

[@circattle]

Necessity is the mother of invention, after all.

[@simonch5140]

I think the story is a bit of an urban myth!

[@LOCOMOTIONNUMBER1]

When I was young in the 1960s my mum put a padlock on the phone as my sister was always using the phone. If I wanted to ring someone I had to get permission first to get the lock on the dialler removed! The phone was a lovely 1930s ‘ GPO pyramid’ Bakelite phone. I remember when the Strowger local exchange was updated to a contactless switching in 1980, the GPO sent everyone a leaflet explaining the slightly different dial tones. The thing I missed was that the Strowger equipment had dirty contacts being an electro mechanical switching, which caused lots of noise, stray staccato clicking of the equipment working and stray other callers messages being overheard. Happy memories of my past!

[@notafanboy250]

Very cool story. Thanks for sharing. I had to look up that phone model. I now want one just so I can feel the ergonomics of it. Seems like it would be satisfying to hold.

[@diecastdragstripracing5297]

I worked in a SxS exchange in the mid 80's, early in the morning you could hear a single call going through the whole floor from one end to the other, during busy times there was a constant noise of switches and movement with thousands of calls being made. Then if there was a faulty connection you could hear it chattering away trying to connect. Good memories, love this old equipment. Cheers 🍻

[@geoffreymawdsley8102]

Very interesting and nicely made! The poor viewer whose mum locked the dial, only had to "tap" the number out with the cradle!

[@hughoneill9929]

Then dash-pots were introduced to slow the cradle movement preventing the required 'dialling' speed being reached.

[@Doctormix]

so fascinating!!!!

[@kenmohler4081]

In 1966 I attended the Army’s 19 week school at Ft. Monmouth, New Jersey. Upon graduation, I was sent to Fort Benning, now Fort Moore, in Georgia. I worked there on Strowger equipment. Late in my time there I was the night guy, stationed in the Main Post exchange and was on call to drive to the outlying exchanges to deal with problems. I really enjoyed that assignment because during the day the switch work was done by civilian employees. At night I really got to work on the equipment. Finally I was sent to Germany where the Siemens equipment was serviced by German civilian workers and I never got to touch a screwdriver again.

[@howiekeegan8804]

Fabulous! Brings back so many memories of installing Strowger exchanges back in the early 1970s!Commissioning this stuff was interesting, especially the special types of switches, for example Coin & Fee Check equipment for the old style payphones! Great to see this operating again! Thanks!!

[@phils2180]

I used to work in a very busy Strowger exchange back in the late 70's -early 80's. The exchange was in an industrial area of the city so a good deal of the traffic was business calls. The noise from the equipment at peak times was loud! In modern exchanges all you can here is the cooling fans.

[@tresparivet6348]

Brilliant! I'm aged about 66 and this is so good to watch. As soon as the dial turned to buttons, no one could remember phone numbers. Today, in 2024, no one knows any phone numbers...

[@Satters]

super to see a strowger exchange in operation again

[@amarjitbiswas3945]

My dad started his career as a manual switchboard operator back in the 70s. Later on when the Strowger systems came, he became a technician. I used to travel with him to his workplace and was fascinated by the clickety-clack mechanism. Dad used to explain me the stuff and basically that inspired me to be an Electronics & Communication Engineer.

[@techydiy]

I was a Po/BT apprentice towards the end of that period and worked in a few Strowger exchanges, so its fascinating to see them again.

[@GlassTTY]

Worked on this stuff in the 1970s at Rugby Telephone Exchange, what a treat to see it here.

[@erenoz2910]

it's crazy how some early electrical engineers weren't engineers at all! this guy was an undertaker but what he invented was a pretty important design

[@ianmcelhinney1530]

A very nice demo. I was a BT linesman but the sounds of strowger equipment is still very nostalgic ☎ ☕

[@terrancecoard388]

What he said in the beginning was exactly what what was thought in Step by Step Switching school in the USAF in 1977. Oh the good old days! You can tell something was off just from the sound...time to break out the spudger and tweak a relay. My career started like this and ended in thirty five years where there was not a sound in the building, no tools or personnel for that matter yet millions of data and voice transactions went on. all you needed was a laptop. After the military, I was an analog multiplex technician and I absolutely loved it! Tracing a tone from the switch through the CO to the radio to find the culprit sure was fun. Especially if a switch tech followed as you use your frequency chart and punch it in the Selective Multimeter. Non mux people thought it was voodoo every time the tone sounded...how did he do that‽ Magic! Thank you HP.. those antiquated WG's were slow! Within ten years we gave up the radios and went to fiber optics. In another ten years the company was selling ISND service that went through an old Central Office that was using rusted copper wires and SXS switches. Those old Telcos learned the hard way that they had to change and now! I see form the comments, lots of old timers still remember. I bet we all miss the sound of dial tone and especially the gratifying feeling you felt when you slammed the phone on the receiver relaying to the person that you were pissed off. The old pissed off disconnect! This was a nice dit of nostalgia...today folks have no idea what it was like. Hell, most never heard a dial tone. One of the most beautiful bit of workmanship I have ever seen was the stitching in the back of an old telephone operator console. Oh...and accidentally touching a pin that had ringing current was not fun...not at all !!!

[@Pacificbell]

I love the sounds of the telephone exchange

[@Shipwright1918]

A "click-and-bang" exchange. Fascinating stuff, thanks ever so much for sharing this demonstration.

[@WouterWeggelaar]

I love seeing this stuff! I worked in Dutch phone exchanges around 2002 and all of this stuff had been phased out with a few exceptions. The people running them have such a wealth of knowledge and I am glad Richard saved these parts from the bin and you gave them a new home. This fall I am visiting the UK and I hope to visit the museum if it's possible!

[@AnalogDude_]

i worked there 1/2 years before, installing the first national fiberglass network, project SDH, the digital part, with lots of fine 0.25mm2 coaxial cables, always 256 (at least) in custom kpn colored 19 inch racks and indeed this stuff was already gone and a Purple Sun Micro systems Unix computer was found in every "neighborhood" exchange, but there where still huge ranks where the wire from the home connections ended up and some ancient vacuum hollow coaxial cable setups that lead to the antennas outside. some had a ships diesel engine generator as backup. i also had to learn the old stuff from KPN or PTT, like soldering, the method of counting, hot to strip wire, etc, etc. courses by KPH spread out over several places by the KPN. it was the best communication network on the globe and probably still is according the CIA world fact book.

[@WouterWeggelaar]

@@AnalogDude_ Same systems then! I was responsible for migrating PDH stuff to SDH and making sure that the two systems were matching (BRIT and OTA) and checking that the resulting orders were made in to COAX, the system that would tell everyone where to lay the cables. Your response brought back memories of that time. Fun fact: OTA did not have an undo, so once deleted, SDH lines could not be put back unless you started over...

[@AnalogDude_]

@@WouterWeggelaar i only worked on need to know basis, i was team leader and we placed the 19 inch cabinets, the pretty fat earth loops on top of the 19 inch racks, powered the cabinets, placed the Marconi 19 inch network rack gear, layed the 4 x 4 (16 coax each) cables and using hamf wire to sew them, placing the inox metal "DC" poles where all the 0.25mm2 coax cables ended and got their BNC connector, sort of coax patch panels ... and repeated that all over the southern part off the country in every neighborhood exchange. ofcourse bigger exchanges used more equipment. the country was divided by 3 companies, Siemens, Ericson and alcatel. making those 0.25mm2 2MB coax cables was kinda Chinese labor. although using a calibrated machine to peal them. it was pretty hi-tech, executed to extreme perfection. all the cabling was done perfect, straight, parallel, etc, etc. someone came to photograph at it all, we weren't allowed to take pictures inside the exchanges. a once in a life time opportunity. not sure if they still require the same perfection now as back then, with these external companies they now employ. employees of KPN themself did handle extreme fat 42 Volt ground power cables and rails. what you mean with undo? start over?

[@AnalogDude_]

@@WouterWeggelaar we had a nice guy, one you wouldn't expect to do criminal things, the typical grandma's boy, as you might know, you had to call a number within a few minutes after entering the exchange and gave them a code, this guy went one Saturday and used his access card to get in to get the fat copper wire we used to make ground loops and stole it, he got arrested by the police and fired. the alarm goes automatically after you enter such exchange and don't use the phone to identify yourself.

[@WouterWeggelaar]

@@AnalogDude_ I'm not sure if they're still that strict. everything went from neat to messy when internet took off and ADSL came in. I remember moving the XS4ALL dial-in banks to another exchange. those racks were put in so incredibly fast that they did not have time to expand the exchange and some of these were on wheels with thick bundles of coax and crosswire plus power dangling. of course the technicians weren't happy and that's why we moved them in to a proper new location once that was ready. Most of my job was cleaning up the old connections and optimising the use of space such that DSL could fit. In OTA (the system including SDH) was a graphical application. If you deleted a bundle of connections, the relationship between all the individual connections was lost and the digital part deleted. it would take quite some effort to put these connections back in, one by one. BRIT ran command line in a terminal, so you could scroll back to find your error and fix it.

[@l.s.6135]

Thanks for the crash course, best regards from across the pond

[@CoopyKat]

This Strowger step was shown for a few seconds in the 1954 Hitchock film "Dial M For Murder" - the first time I saw that scene I thought it was super-cool, I could tell that is how calls were completed at the phone company at that time.

[@huntabadday2663]

Multiple videos of you just dialing the thing, now I know you REALLY love this thing

[@Tomsonic41]

Until 1995, our local telephone exchange was one of these step-by-step systems. I used to wait for the dial tone to stop, then you could hear the background noise of the exchange - other people dialling, faint snippets of people's conversations. I wish I'd recorded it, but didn't have any easy way of recording the telephone back then!

[@craiggemmell4559]

I find this hard to believe, I worked on SxS (Strowger) exchanges and never heard or saw this scenario. Sometimes you'd get "doubleswitched" where 2 switches stuck on the same outlet and you'd get crosslines but the way you expalin it doesn't seem possible to me.

[@user-hy2ry3if8h]

Amazing video. @5:25 - This is enough space for full server rack, able to handle hundreds of thousands of calls today. We wouldn't be here if it wasn't for Mr Strowger

[@dash8brj]

I did work experience in a telecom exchange (Australia) and back then they had this system and I often spent my free time watching the calls being placed. In a large country town there would be 10's to 100's of calls being made a minute, so a telephone exchange with this equipment can get very noisy!

[@qweasd909]

Thanks for sharing of information.I am a retired telecom field engineer,and my first Phone system was Siemens& Halske direct Phone system similar als this.Later cam the indirect system of Bell (7D,7E & 7EN) than folowed by the SPC sytems such as Ericsson 's AXE, Alcatel Lucents 5ESS,Philips PRX and Bells system 12.But the earlier sytems was memorable for me.

[@simontilling7906]

Wow that takes me back to my days as a T2A in Liverpool doing ANs and Switch bashing

[@kerzwhile]

This is excellent!! Much better production of this historical preservation!! This will be viewed in schools for hundreds or thousands of years! 😉

[@seamusellis1450]

Absolutely love this ...( will be coming to look when you reopen and would love to volunteer as we are only down the road in Dover). Back in the early 80s BT had open days and mum took me to look round the Strowger exchange in Stour Street in Canterbury. I remember the noise being incredible !!. The engineer said it would all be replaced by computers in under 10 years which of course it was...

[@lesco_music]

I wanted a device like this since I was in a telephone museum. But I do not have the space for that. Instead I’ve got a Kinoton FP30D up and running 😂 You can look it up it’s an interesting device.

[@mhbh1979]

Awesome, I worked in BT exchanges around 2006-2010 installing metering for private tennants. Orange (at the time), Virgin, O2 etc. The old Strowger stuff was still in the large exchanges such as Swindon just not used as 21CN and the tennants need hardly any room.

[@212MPH]

Brings back memories of my days on stronger in the early 80s.

[@ronaldtaylor2857]

The town was actually in Laporte Indiana. Stroger sold, or gave the system to general telephone and electronics, and they use the city of Laporte as a test bed. It was this first city in the world to have a dial telephone system.

[@HappyBeezerStudios]

The most interesting thing that modern digital phones are missing is the fact that you could also use the phone if your electricity was out. The power came from the exchange.

[@Colin_Ames]

I love this kind of stuff.

[@montlejohnbojangles8937]

That was super cool! I had no idea they were such a mechanical demanding object. Must have needed a crazy amount of maintenance, right?

[@Xcieg]

I would of loved to see a room full of these.

[@stephenbrown9998]

Thank for the listen although I was on extnl subs app and line it was good to hear strawger again

[@SuburbanDon]

Thanks for posting this. I love this stuff !

[@michaelcostello6991]

Thanks for showing this, A wiring diagram would have been nice also for further clarity

[@Helgardt6189]

We still had a exchange like this in Roodepoort South Africa up an till 1997.

[@steverushforth7009]

Brilliant, the dial tone motor is very large to move a few contacts.

[@1harryrobert]

It generates all the other tones as well

[@Musikkeller-Innsider]

Thanks for the interesting techistory!And now please show the SMS implementation ;-p

[@NecromancyBlack]

So when the selector goes up the the level you dialed, it then goes across and stops. Is that it looking for another free selector? In these case there's only one so it'll always stop on the same point? I would assume that's also why the final one doesn't automatically go across and you have to dial in the last number, cause it's not going to go searching for a free selector.

[@LOOKMUMNOCOMPUTER]

You are correct

[@bertiebaz5455]

yes, this is just a demonstration set up. There would normally be racks full of each type of selector so a maximum of 20 (10 upper contacts and 10 lower) outlets to the next stage selectors. Now let's talk about grading......

[@BTTT-c9q]

Great demo, thank you 😊

[@carlmcphee9947]

I remember the old rotary phone in the 1980's

[@joebarrett4353]

so well explained. Thank you

[@Skibidi_Male_X]

How were numbers assigned to each customer? How were they stored ?

[@nickpetralia223]

there's a cool thing you can do if your fast enough at counting. each step those rotors steps up to equates to a dialed number. for instance in this video from what i heard they dialed 34425. the last rotors is tricky because its special. it steps up to the number that was dialed in this case a 2 but then waits for the last number to connect which i believe was 5. now that number looks odd but back in the early days of phones local calls all were on the same network so you only had to dial 5 digits to call locally.

[@DiHandley]

I remember it so well. Where did the time go? 🙁

[@ronaldtaylor2857]

The town was actually Laporte Indiana. I am retired from my IBEW local union 531 Laporte Indiana.

[@8enjam1n]

My dad worked for GPO and BT, a lot of time at the Staffordshire college near Stone. He died last year and I now have his old tools for servicing these exchanges. Things like go/no go guages for example. Are they of use to anyone? I could take photos or video of them if anyone's interested. Cheers

[@korma9732]

Spent many weeks at Stone over the years. Great place.

[@binface9]

Fascinating

[@DjSubstain]

One problem was that if one person did not hang up, the line would still be connected, so the person who hung up can't pick up and make a new call. They would still be connected to that other line. If I remember correct...

[@ObviousSchism]

Yes but this was only the case for the called party - the caller had control of the call. However, I believe that measures were introduced to mitigate this with an enforced cleardown after a certain period of time.

[@DjSubstain]

@@ObviousSchism You are right.

[@geoffreymawdsley8102]

Are you in any enthusiasts group? I would like to meet strowger enthusiasts. I got interested when I was 14 in 1961 and still am!

[@tolstoy431]

IT is AWESOME.....So ADVANCED......

[@barnabynorman157]

This is great!

[@eddiejones.redvees]

My first day at work after leaving school in the 70s was helping to look around Lancaster house telephone exchange Liverpool for Selectders to hang on the new racks in the 10 years I worked for plessey on exchange construction I Learnt to do Most jobs from the ground up including how to adjust the wipers into the banks. Little did I no I would end my working career at the other end of the network safety checking poles after 40y work for the GPO BT Openreach the pole testers job was a higher paying rank that was why i volunterd to do the job and most of the time I did it I was my own boss and left alone to look after the 30.000 poles on my patch

[@yigitcan824]

Amazing ,thanks

[@FrankJohnson-ye8lt]

Why do the Selector lights remain on during the call? They never did when I was a telephone exchange engineer in the 60s. Good memories though.

[@THISMUSEUMISNOTOBSOLETE]

the lights usually would only be on the first switch. but they have been modified, like all of the other switches now to be lit up for demonstation

[@johnacheson9913]

The caption is incorrect. They are 2000 type selectors (not Strowger selectors).

[@THISMUSEUMISNOTOBSOLETE]

yep you are right. but both are used colloquially. even by ex bt operatives.

[@PandaKattPk]

LOVE THE MICKY MOUSE PHONE! Lol will you pick up the phone its ringing hehe Much LuV LMNC!!!!

[@hariranormal5584]

Absoueltelty beautiful

[@RegebroRepairs]

It seems to inefficient to use one number per switch. They are clearly two dimensional and can handle two numbers each! Maybe it's for demonstration purposes...? Ericsson made switches that were a lot larger, I think they could handle three number each. One number up and down, one left to right, and then an arm shot out to different depths for the third number, IIRC. Saw one in a museum once.

[@LOOKMUMNOCOMPUTER]

It’s demonstrating how it was used the across motion on uniselectors function is for hunting for free switches for the next number. However The last one has 2 numbers

[@robert574]

I see that there are 10 wafers in the set and there are a pair of wipers on the shaft, one on the top and one on the bottom of each wafer. I see the contacts on top of the wafer, is there a second set of contacts under each wafer? And then there seems to be a duplicate set of 10 wafers and wipers above those. What does the second set of wafers do?

[@LOOKMUMNOCOMPUTER]

in these switches yes contact on top and bottom. there are 4 contacts which are the + and - of the phone signal line. the P wire which transfers functions and also the M wire is for the meter which goes up to charge the caller

[@MrJob91]

This thing is solonoid magic

[@swainscheps]

I’ve watched several videos on SxS and the action is explain well, but the big picture is still eluding me. So let’s imagine a town of 10,000 people and a single central exchange where everyone has 5 digit phone numbers. That means in our central exchange a single phone call requires 5 uniselectors, correct? So if we have 10 level 1 selectors, 10 level 2 selectors and so on, there can only be maximum 10 phone calls in progress at any one time, right? I guess I’m confused about how / why the central office equipment is arranged…so every single phone in our town is connected to a special final connector?

[@bertiebaz5455]

Each final selector has access to a block of 100 numbers (10 levels x 10 outlets). There are 10 final selectors on a shelf but then there can be more shelves on the same group depending on how busy that range of nubers is. You can always add more switches if callls are failing due to not enough final selectors. Same with the 1st, 2nd etc selectors, there wouldn't only be 10, usually racks of them. You are correct that with a 5 digit number the selectors would all be held for the duration of the call, in this case 4 selectors - 1st, 2nd, 3rd and final. Hope this isn't too confusing

[@U014B]

ASMR Strowger Switchbox Dialing Every Number From 00000 To 99999

[@ashreid20]

how is the number sent from the phone to the selector, is it like a 'cv' scale? 1v per number, or what have you

[@ObviousSchism]

Its simply a sequence of break/make pulses caused by the telephone dial returning to its starting position under spring tension and using cams to operate a mechanical switch as it does so - one pulse for digit 1, two pulses for digit 2 and so on. Later push-button phones created these pulses electronically.

[@ozonewagle]

It'd be helpful if someone explains me the following scenerio. In this case subscriber A calls subscriber B. When the A was dialing, it generated pulses which made those (thingies) to switch to a certain level and the led were on. Suppose the call is being carried out between A & B. Now at the same time subscriber C attempts to call Subscriber D, as the lines were already occupied as indicated by those LEDs, what will happen in that situation? The main point I'm not getting is, I am assuming even this small system can handle multiple calls at a time, and wondering what happens if more than 1 calls toook palce. Thanks.

[@kenmohler4081]

There are racks of hundreds or thousands of these switches. What was left out of this demonstration is the first switch you encounter is called a line finder. It senses that someone has picked up their phone. The line finder “finds” that caller and connects them to a first selector that send back dial tone. You now have your very own path through the exchange. The call progresses like you saw until the final switch called a connector. The connector is the switch that takes the final two digits and connects to the called telephone. So hundreds of calls can be connected at the same time. A Strowger step-by-step exchange was a noisy place with all those switches clicking around and completing calls. With experience, you could hear a malfunctioning switch amid all that clatter.

[@jonnymoka]

Sam has aged quite a bit.

[@THISMUSEUMISNOTOBSOLETE]

haha

[@zordmaker]

Thats 2000/SE50, not Strowger.

[@THISMUSEUMISNOTOBSOLETE]

modern colloquial

[@tertia0011]

I had opportunity to see ancient 'step by step' switched telephone exchange in operation before its decommission. Lots of clicking & whirring, unlike modern digital exchanges which are exceptionally dull & boring by comparison. Man & dog exchange - dog prevents man from meddling with exchange equipment. Man is there only to feed the dog.

[@somebloke5565]

Pink Floyd "Money"

[@dxtxzbunchanumbers]

Anyone else get a Pavlovian reaction waiting for Pink Floyd to come on?

[@terrancecoard388]

How can you not? Money!

[@GetInGarage]

cool memories, was a tech in 85

[@RohitKanaujiya-z8c]

Rohit 786📠📠📠💤🛸📼📼🗾👁️🗿🦿🦵🦶🫀💿💿⚙️⚙️📡📡🤝👀👀👀📡👀⚙️👂🧠👣🤩💽🛠️🧲🖲️🤳📇💺📐📇🤩