AT&T Archives: The Step-By-Step Switch
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- Опубліковано 24 лип 2011
- See more from the AT&T Archives at techchannel.att.com/archives
The purpose of this film was to show employees, back in 1951, how calls were automatically switched through an SxS office.
This film gives a general appreciation of the importance, complexity, and cost of switching equipment in an average 1950s telephone office. The path of a call is illustrated as it runs through a demonstration unit. "Careful adherance to Bell System maintenance practices" is stressed. While this is only part I, Part II eventually showed the equipment in various types of use, and Part II showed the internal circuit operations.
Switchers today are digital and look drastically different. These systems at this time were still not even transistorized, so this film shows a system that's not only years back in time, but many generations back in terms of technology.
Producer: Audio Productions, Inc.
Footage courtesy of AT&T Archives and History Center, Warren, NJ - Наука та технологія
When I hired on to AT&T (Southwestern Bell at the time) my central office had just been converted from Xbar to 1ESS. When I retired from same central office over 36 years later it was DMS and we were testing interoffice fiber for 100 gbs circuits. I trained my entire career to keep up with technology. It was both challenging and rewarding.
Is this you?
ua-cam.com/video/1G2keZBSZmY/v-deo.html
And when did it dawn on you that it was always about mass surveillance?
I left Lucent in 2003 we had the 5ESS, funny you mention the DMS, that was a Nortel switch, used to be called the big Brown machine, nice to see comments like yours, brings back good memories, I started in the telecom business in 1970 at GTE Automatic Electric Co, used to engineer step by step central offices, I am now 73, best regards to you!
@@aybee63 He's right. Nothing whatsoever to do with communicating across town or across the country, for interstate business, convenience, or friendship. What a massive genius...
I have similar experience starting with manual patch cords, analog multiplexing and finally digital fiber. Very fun and amazing!
Don't laugh, these switches were very reliable but they needed people to maintain them. I worked under the old Bell System, back in the day when employees took a lot of pride in their work. It was a very strict workplace but we were proud to say I work for "MaBell".
+Bri G. EMP Proof !
+Bri G. I love learning about analog... It seems so complicated compared to our new age digital solutions. I can completely see where someone would have huge pride in maintaining these systems. Very technical, precise and methodical skill set required to keep machines like these running. Calibration is mission critical, both then and now.
I never got to work on them, they were being taken out of service in 1980's. It did require some skill to maintain them. the New switches when something goes wrong the techs remove the bad circuit pack and plug in a new one.
everything is interchangeable, modular, oh and soon-to-be refuse. Is Salvage still a real word in the dictionary, or was that excised with the digital age?
The PBX at my office in 1982 was a step-by-step PBX and the PBX operator connected incoming calls at a cord board. My keyset phone was rotary which made using services that required Touch Tone to be impossible. So I bought a telephone set microphone from Radio Shack that had Touch Tone buttons surrounding the microphone. When making calls, I dialed 9 on the rotary dial to get a second dial tone from the central office and then dialed the number on the Touch Tone pad surrounding the microphone.
Fun Fact: The first step-by-step switch and indeed the very first automatic telephone exchange was invented by Almon Strowger.
Almon Strowger was an undertaker by trade. He became convinced that the manual telephone exchange operator, who was the daughter of the only other undertaker in town, was deliberately directing all calls for "the undertaker" to her father's practice instead of dividing them equally between the two as was standard practice at the time.
Strowger decided that he needed to invent a way for telephone customers to dial the number themselves and used cut out pieces of paper to represent the electrical contacts so that he could work out how the equipment should work.
If I remember correctly, Strowger was granted a patent for his automatic telephone exchange in 1929.
Strowger's exchange required two extra wires from the exchange to each telephone to carry the dialling signals, but some clever lateral thinking allowed for using the same two wires for nearly all signalling as well as for speech.
That was actually fun to read. Thank you.
The very 1st strowger automatic exchange in the world was installed here in LA porte Indiana in the 1890s we have some of the original equipment at our museum...
@@a1wireless1964 If that's so, then I must have been wrong about the date of the patent. But the earlier the patent, the cooler it seems. :)
@@melkiorwiseman5234 It is indeed cool and it indeed is from the 1890s!
@Heroin Bob and the Maple City Four.. Freeman Gosden and Charles Coralle, Amos & Andy! got their start on WRAF, the radio station in 1920s. Also the home of Jiffy-Pop! Popcorn
"good design, a well-made product, and accurate adjustment means good service" wow who would have thought that would still be relevant today
Certainly none of the big companies
Whats relevant today is replacing all the "Telephone MEN who know their circuits and equipment thoroughly"
@@charlesbaldo I notice at 1:01, it's "telephone men", at 1:30 it's "telephone people", and at 6:50, it's "telephone man" again.
@@charlesbaldo I have worked with a range of people while working in I.T. and can say from experience that a persons gender has nothing to do with the pride and effort they put into their work. Most of the time its the executives deciding to cut time and funding to products and services that previously received lots of attention and care.
@@sams8549
Having been a software engineer for 35 years, I don't disagree. What i have noticed is that gender does seem to gather around certain functions. Engineers are mainly men, Quality assurance are a mixture with women being the best. My wife is a QA engineer for digital radiography, i jokingly say she can find something wrong with anything. Management seems to be mixed but HR is heavy female.
My point in the comment was that this film would have been canceled in todays culture.
Despite having thousands of parts, there’s a beautiful simplicity to the concepts and physical directness of the system. It’s fascinating to see the creativity that goes into mechanical logic systems.
It mirrors the difference between a steam locomotive and a diesel-electric.
Today, an entire building full of those switches can fit into a small electronic box the size of a loaf of bread. Amazing progress.
That said, there's definitely something to admire about the old mechanical system.
Oh today it can for into a box even smaller then just one slice of bread ;) it's crazy how powerful stuff has become
bigloudnoise can’t something like a modern flagship smartphone do it, given the right connections?
So many jobs gone. Ah the progress.
Abu Baker - so much wasted time saved.... oh yes, the progress
And then you have... so many jobs created from the progress... oh... the progress...
@@John_Da199 yeah just forget about the millions more it's created you boomer.
Worked on these, as well as Planel Swt, #1 Crossbar, #5 Crossbar, ESS in my 47 year career. AT&T was a family back then, not like today.
& all the old school management that cared about u retired in 1990 @ the call center in Bell of Pennsylvania, Pittsburgh.
Must have been awesome
Man, mechanical switching....That is a trip. Just astounding the number of tiny parts involved.
Yeah, so how did VoIP replace this?
Smaller, cheaper, and faster.
These systems were large, power hungry, and not very smart. It only supported simple telephone calls, and had no common control or advanced routing of any kind. A VoIP system requires a small box connected to the internet, which can do orders of magnitude more. The only thing a VoIP box can't do is ring a big bell or work when the power is out. While the older systems were fun to watch and listen to, they are completely obsolete and most people don't care.
It would be nice, however, to still get a voice signal that doesn't sound like 2 bits in 8khz or less that only sometimes get through.
@@user2C47 Weirdly, land lines are becoming more of an inconvenience these days because of analog compression being so damn lossy compared to digital. It can absolutely butcher the sound quality. Most land lines, at least in the US, are moving over to VoIP because it's not only cheaper, but sounds better in the end.
Tons of Pittsburgh Switchgear? baby!
Amazing all the little parts that were machined
I today (February 2017) working on this kind of headquarters, you might think it's impossible, but it really is true. I live in Serbia.
sinisa mitic really? You still use step by step in Serbia?
use of such switchboards rail. I work every day on it and can send you footage from the workplace, if you like? Where do you live?
Wonderful to know such equipment is still in use.
I am a little late, but if you could pm me, I would be very interested. I had no idea there were still switches like that so close to me.
could you email me a picture to admin AT dc4 DOT us
I am very interested!
That was the time where a bug actually was a bug.
yeah, the ABC computer got the first bug (a moth) in it
Hence debugging
Buttle?
@@austinfernando8406 I believe their notebook even had the actual moth taped into it
Kyle Nally also their notebook never crashed.
I worked for South Central Bell in the downtown Nashville, TN central office 50+ years ago. We had four exchanges of step-by-step in that office: 242, 254, 255, and 256. 244 was a crossbar switch, and 259 was Nashville’s first ESS. I started as a frame man. Our MDF carried all six of those exchanges. Twelve feet tall and half a city block long. That means a jumper wire connecting the terminal on the horizontal or number side of the frame to the assigned terminal on the vertical or outside cable side could be over 200 feet long. There was such a jumper for each one of the 60,000 numbers in our CO. If you figure the average length as half of the max, that meant there was around 1200 miles of jumper wire on that frame, or enough to run a single two-wire jumper from Chicago to Houston.
Good stuff, your Main Distributing Frame, what did you have on the Vertical side for protection, gas or carbon arrestors? Were they Cook or Reliable? Did you have an IDF as well ?
@@dc10fomin65 since the frame was the same vintage as the step switches, they were protected by carbons. Don’t know that I ever noticed the manufacturer. I would have assumed Western Electric like all the switch gear. There was an IDF on the second floor
@@LandNfan Amazing to catch you on the air, I used to work for GTE AUTOMATIC ELECTRIC and did a lot of C.O. engineering, watching these videos brings back many memories, thank you for your comment, best regards.
From 1962 thru 1965 I was a dial central office repairman in the U.S. Army, both stateside and in Korea. Our telephone exchanges utilized this type of equipment and it was referred to as Stroeger stepping switches. When I got out of the Army I applied for a job with New England Telephone (their name at the time) and when I told the personnel guy what I was experienced with he chuckled and said he didn't think there was any of that equipment around any more. I declined his union job as a floor sweeper.
The name's Strowger. Almon Strowger. ;)
"Do you expect me to talk?"
"No, Mr Strowger! I expect you to dial!" :D
@@melkiorwiseman5234 Nice one; worthy of a Commander McBragg punch line!
We had step switches in our little town in Wisconsin all the way until 1992.
I used to maintain Strowger switches for GTE in California. I don't miss maintaining Strowger switches for GTE in California.
@@somedumbozzie1539 I'm not familiar with crossbar equipment or cabling, but I know all about engineers changing design parameters midstream, and "re-tasking" equipment "experimentally". Frustrating stuff! While all other COs were installing new EAX/ESS switches, I was installing new digital-to-analog circuits, so that our subs could use 'touch-tone' technology.......Interesting stuff! I was only 21 at that time, and knew that I'd eventually be given the opportunity to work on/with the "new stuff". A job with the City of Los Angeles exposed me to microwave radio and fiber optic tech......I learned a lot for a decent wage. Plus, they still actually had some SXS equipment for me to fix.....life was good!
When I was a telephone linesmen/cable splicer in the US Air Force from 1980 to 1994. A lot of this equipment was still in use. The first time I walked into a central office back in 1980 at Norton AFB, CA. There was a whole lot of noise in there . I asked the telephone tech about it and he replied, What Noise !. After we had a good laugh. He showed me around the CO and explain how all this switching equipment worked. I learn a lot that day.
Similar experience but in Germany. The US military had Stepper equipment made by Siemens and based on a design produced for the "Reichpost" in 1940. I'm sure it was quality stuff when new but, by the late 1970s, it was just worn out. It was noisy both mechanically and electrically -- we called it "Hitler's Revenge."
When I was growing up, my neighbor worked for AT&T Long Lines. He used to give me old telephone parts including switches that I wired up to make a small phone system of my own.
Later as an adult engineer, I did work for SNET and New England Tel. There was a lot of SXS central offices in operation well into the early 80’s. I did a lot of work converting offices from mechanical switches to ESS.
One thing we learned was that the electronic equipment needed air conditioning. Before that, telephone central office buildings were not air conditioned. This drove up power requirements and required new electrical services and larger emergency generators.
Of the 200 or so Central offices in Connecticut, I probably did well over 100 of these conversions.
The most common ESS was the Western Electric #5ESS They produced thousands of them in the 1980’s. At each site, a temporary building addition would be built, the new ESS installed and wired. When it was operational, the old SXS or crossbar switches removed and the new ESS was slid into the old building while in operation. The cables were then shortened, by “half-taps” (splices) and the temporary building removed.
An enormous amount of work and cost.
Bill Moran where have all those switches gone? It would be super cool to get some of those to do something with.
A few found their way into experimenter’s shelves, but the vast majority were scrapped to recover the metals they contained. I remember truckloads of them being hauled off for scrapping.
any tips on what to brush up on getting into CO work?
Where I live this Step exchange was fully dismanteled in the early 1990s when all of the exchanges went to digital equipment. Not only was this mechanical stuff noisy, but it housed a lot of space. Our local phone company got rid of dozens of buildings around the city as they no longer needed so much space. It is amazing how this matrix of wires, magnets, springs, and mechanics eventually connected phones together.
You can't do this anymore, but when I was a kid I was inspired by this episode of Gilligan's Island where a phone cable got washed ashore by a storm. Their dialing mechanism didn't work correctly.
So I experimented by tapping the reciever to simulate the pulsing that the dial normally makes. I called my Grandma; It WORKED!
It should have worked for the Professor too.
Like, the button in the cradle that hangs the phone up when you put it back on the hook? That's some inventive thinking! Cool!
You can't fully understand the impact of the computer chip without watching videos like this.
Funny thing is, even to this day electronic phone switches for analog landlines have to be backward compatible to dial pulses in case someone is still using a rotary phone somewhere.
***** Yeah, well, in Germany they do. Even the VoIP capable cable and fiber optics modems still do. I've tried it out myself and it still works.
OolTube02 like me
I use decadic dialling all the time here in Sydney right now
yes, and it takes more computer time to count out dial pulses than to simply process a tone burst. When the telcos had to buy touch tone conversion devices to feed step switches, they put a surcharge on your bill if you wanted to use a touch phone. Now that it is better for the telco if you use touch tone to feed the computer, many telcos still charge extra for tone service!
@@bichela
*analog
I took a rotary telephone apart when I was probably 7 or 8 years old. It's amazing how many steps there were to this system. Hundreds of contacts and springs... Almost like a washing machine timer if I remember right. It's so cool to know that those contacts inside the phone, pulsed a signal in real time to these switches. Makes a lot more sense. An in old timer told me he could hear the switch box at the end of his street chattering all day long lol
I did my apprenticeship in various exchanges in the early 80's, and got to work on Strowger (what you call SxS), crossbar (which were huge lumps of metal bars with springy needles), the updated crossbar (which was huge arrays of reed switches doing exactly the same thing as crossbar), System-Y, and System-X (which was the first all solid-state equipment, and was insanely static sensitive)
What's not mentioned on this video is the current consumption of those Strowger systems!! From what I remember, Leeds exchange in England drew something like 200 megawatts during busy hours, and the system had battery backups (huge lead-acid batteries) in the basement that would keep the exchange running at that current usage for up to 30mins until the diesel generators span up. Also, the heat from all those actuator coils in the electromagnets made it stifling in the summer.
Those battery rooms were disgusting places too, with the stink of the acid, and as an apprentice guess who had to check the electrolyte levels regularly :)
Ah, nostalgia...
actually, I was there when they went from strowger to the first common control reed switches. While strowgers take a lot of current to move the shaft, that is just momentary. and goes to zero with no traffic. The early computer controlled switches used a LOT of power to run the multiple computers and memories, and a significant current to hold up the reed relays of the network for the duration of the call, as well as the loop current to customers, which remained the same. The consumption of old and new switches was comparable, clearly displayed on the 50v rectifier output current meter. Even now, the digital multiplexor technology uses lots of power for the computers and the network, which consumes power even with no traffic.
Yes, that seems to be often missed: older systems had a VERY low idle current (effectively just the leakage on open wire lines). Progress eh?
5ess had a room full of lead acid batteries to run the 48volts for the switch. Working on 20 year old memories though.
man comments like this just adds to the video by blowing my mind. its crazy the kind of terrible ass workplaces existed that i could never think of existing haha.
Remember pay phones on the street, before that telephone booths? Remember when having to wait for a dial tone? Remember the party line shared with the neighbors across your Ally? Calling operator to connect a long distance phone call?
Take a minute tonight to bring such things back to your grandchildren's memories.
OMG, does this video bring back memories. I was hired in '78 to install SXS in Eureka, CA. While the rest of the state was removing SXS and replacing it with quiet ESS switches. We ran lots and lots of cable, wire wrapped and soldered at the main frame and between the switches was another array of specialized wiring to connect the switches. In the 80s we were able to convert the SXS switch to dial tone by adding a small box to the rear of the switch. Those were the days, before divestiture.
judy i can't grasp how this worked. does that mean each selector had only 9 levels to go up? So how many connections on each level? it could be more than 9 right?
And how were selectors set up? Was there a row for the 1 digit, then a row for the 2 digit and so on?? or could a second or third selector serve for any number?
When you said "dial tone " could be added with addition of a converter to the selector, I think you meant " touch tone " could be added. The dial office already had dial tone.
Why were they installing SXS in 1978?
@@TechHowden there's a SXS you can actually dial into it right now and hear it in operation. Its really cool
For the time, that was some impressive technology.
When I was a kid we went to the open house of UTS and toured their building. The engineer who explained these said the nickname for them was "bang and click".
Fun fact: I forget the year or the Philadelphia suburb, but at this particular office these devices went silent for 15 minutes once a week, like clockwork, unplanned. It took a few weeks to realize the problem: none; people focused their attention to the "Amos and Andy" radio show, when it was over normal use returned.
Some of my college friends learned how to defeat a dial lock (when the owner of the phone wanted it to be answer-only) by lifting the handset and hitting the hang-up button in the proper rhythm to simulate dial pulses.
Allan Richardson, Yep! Used to work the midnight shift at a local factory where dial phones were the norm. They used to insert those locks on the dials so no outside calls can be made. Little did they know I was a percussionist and knew my rhythms well (played a lot of odd time signature fusion) so pulsing a number set through the hand receiver switch was no big deal... used to complete calls for all my co-workers as well... lol.
As seen in Silence of the Lambs.
Yea i used to dial like that's all the time just for the heck of it.. one time i dialed to many digits or something and a service man cut in.
This was called cradle dialing. It was a pretty common method of defeating dial locks back in the day.
@@tmastersat Some exchanges had automated circuits to check the dial. Extra digits we're usually ignored. It is possible that the service man thought you were attempting to bypass security and make free calls.
Edit: Could it have simply been a recording?
After today's 6 hour outage call on our VOIP system at work were we spent about 4 hours tracing packet losses. It would be so refreshing to just go to the mechanical room to see which relay failed vs tracing some random loss 700 miles aware on a MLPS line that nobody could figure out.....
This system was in use in rural Maine through the 1970's. Very noisy, but fascinating to be in a room with dozens of these devices running simultaneously. I believe this was the first system to be put into wide use after operator-assisted calling ended.
Stumbled onto these vids and it brought back memories of my father who worked for NJ Bell in switching offices just like this one! I had parts of them as toys! The noise in those buildings was deafening, I've never heard anything like it. They broke down often as he was called in many a times in the middle of the night of course they paid well. Plus, as a kid I thought all the tools we used around the house with NJ Bell on it was normal, I think I used up my last roll of electric tape about a year ago and my Dad retired in 1985 after 40yrs. Great stuff!
+rob condit My father and grandfather worked the AT&T > Bell Atlantic > NyNex what not in NY. I grew up surrounded by the logos on various things. I now work in telecom and have my grandfathers Bell System (38-Y-3991A) stencil at my desk, which has the same shapes I use in Visio to draw call flow diagrams for Cisco apps. The evolution of this technology is so cool.
Just watched the video again and its amazing the engineering that took place to make it all happen, sure didn't understand it as a kid!
When referring to Japanese, Chinese, and Korean, the modern term is _East Asian_. For Burmese, it's _Southeast Asian_. For Indian, _South Asian_. For Asian Russian, _North Asian_.
My dad worked for our local phone company. He would get called out on trouble which was almost always one of these switches getting stuck when the person hung up (like around the 2:00 mark). He taught me how to find the stuck switch and flick it back into place, and he'd collect his OT for fixing the trouble lol!
@sportster1988 In the Miami wire center you could tell what time it was by the noise from the switches especially if you were on third shift. ANd listening to that damn trouble gong ringing all night long. One night I couldn't turn it off and I looked and every bay had a trouble lamp. Lightning had struck a 1212 cable outside and blown all the protectors out to ground and every line finder was operated. The only thing I could do was pull all the heat coils once I figured out what cable was hit.
Remember Calling Party Hold? We'd call a crappy restaurant and leave the phone of the hook so they couldn't get take out orders until the testdesk had someone put a toothpick on the calling party.
Wow, I never realized there was so much MECHANICAL engineering involved with the early phone system. That's some fine engineering there! I'm an electronics guy myself, but I have much respect for the Mechanical people.
When I was a kid, my dad was a CO manager for C&P. I would go to work with him sometimes in the summer, and often he would hand me a bottle of solvent and a pack of long, wood-handled q-tips and send me into the stacks to clean contacts on these switches. I thought it was great fun! That was a loud place to work though. Imagine an entire building with thousands of these switches all clattering all day long...
Tapping out a number was a useful skill when a phone had a dial lock. You had to get it just right or you’d get a wrong number. The lazy way was to only learn to dial zero (10 taps) and ask the operator to connect you because “something is wrong” with your dial.
that and the fact an old pay phone was simply a Ground start trunk with a mechanical coin switch on the dial.. if you could momentarily ground the ring lead and then hookswitch the number you could call for free every time :)
@@eldoradoboy Old Abbie Hoffman Yippee trick! Those were the days....
This is absolutely astounding. As a kid, I used to like pulse dialing not with the rotary dial, but with the off hook switch. To dial a 7, I’d just press the off hook button quickly 7 times. I don’t know why I did this, it was slow and error prone. I was weird. But I remember very well using these systems. It was really crappy in terms of audio quality, but it worked when it needed to. It was not uncommon calling my friends on a line with excessive background noise I’d tell them, “this line sucks I’ll call you back on another one”.
This system still amazed me. It looks like a high maintenance and troublesome system but it worked. You can even call the mainland with it (I was born and raised in Hawaii so making calls to the mainland was really neat and expensive). With the advent of Lucents amazing 5ESS digital switches and DTMF, that made pulse dialing irrelevant pretty quickly.
Pulse dialing lasted a long time in other places. I believe some of the former Soviet countries still have it. Although the last time I personally used one was 12 years ago.
In 1966, I used a telegraph key to interrupt (pulse dial), a transformer, two amplifiers, headphones, and a microphone to make my "telephone" in my bedroom.
When I was young, we went from the operator asking "number please?" to a dial system when we got dial phones back in 1956. This was an example of electronic (actually electro mechanical) technology being reliable from the early days on for many years without any problems. I lived in Huntington, NY at the time.
Even today with our "digital miracles" This and the original automatic transmissions still freaking amaze me!
Yes......The Strowger switches and their ancillary equipment were fascinating. The engineers were geniuses, and had a remedy ready for any design flaw imaginable......
I worked on one of these type of telephone exchanges in the Australian Navy in the 1980's, all I can remember now is they are called 'group selectors' and line finders. Quite good to work on, mostly cleaning contacts and adjusting the mechanics.. There were exactly like this one.. I think from memory it was called a "10-100 exchange".. thanks for the vid..
I was involved in the change out of much of this electromechanical equipment during the 80's and 90's. It was amazing to see one line of digital equipment replace an entire room full of equipment. Put a good many people out of a job in the process.
Was the old equipment "confiscated" by the phone companies(after removal)? I'm really interested in getting my hands on one of these old selectors or even an old operator manual.
Patrick yeah it would be super cool to have one of those selectors. There's probably a bunch of those in a old warehouse somewhere.
Were these switches often referred to as ‘decade switches’? I’m a middle aged electrician with many years of prem cabling, and early in my career I worked with an old Bell technician who taught me a tremendous amount about switch rooms, MDFs, terminating and such. I’m 50 now and still use that knowledge daily. Anyway I recall him talking about decade switches
@@abandonedcranium6592 , probably sold to a 3rd world country.
IOW, folks, the phone in your house was actually an integral part of the switching system that routed your call. Now, your phone simply says to the central switch, "I pressed the numeral nine" (if you have a land line) but back then, a rotary dial phone actually sent nine pulses to move switches in the CO nine positions. I used to own one of these Strowger switches. Note they only work in the position shown. They require gravity's assistance to work right.
I came into the field as the last of these were going away, I dought a switch tech of today would even know what these are, let alone work on it. They were a work of art.
I worked for Telecom Australia as a communications technician when the exchanges had step-by-step equipment, like the others who posted here we had pride in our skills and workmanship.
Eventually step-by-step was replaced by the Ericsson "crossbar" system which had central control units albeit comprised of electro-mechanical relays - a foretaste of the future's all-electronic systems.
We used to joke about the "telephone exchanges of the future" which would have a staff of 2 manning them - a man and a dog (the dog to guard the building and the man to feed the dog). I used to think "Naaah it'll never happen".
I left Telecom ages ago but I notice the modern exchange buildings in my area seem to be unmanned and visited by maintenance crews.
We called them Strowger two-motion selectors when I joined Post Office Telephones (later British Telecom and then BT), in the UK in 1973. Some of the large exchanges had selectors that looked identical to these, but most had a more modern version, with a squared off front and was not as tall, which I believe were referred to as '2000-type'. In UK exchanges, the hunt for the initiating subscriber was done by a rotary uniselector, but otherwise the process was pretty much identical to that in the film. They were indeed subject to intensive maintenance, and every selector in the exchange was routinely 'busied out', removed and tested, with adjustment and/or replacement of components done as necessary. I only stayed for about 4 years, and crossbar was making its way into the network at a rapid pace. I can remember how much cleaner, brighter and quieter the x-bar exchanges were than the old strowger ones.
I joined in 76 as a TTA. I remember bank cleaning 2000 type switches and uniselectors for many hours at a time before progressing to the 'New' Crossbar TXK1's
@@wino99999 Yes, I was a TTA when I joined and left shortly after being made up to T2A. I vaguely remember the bank cleaning, but mostly ended up maintaining the switches and relay units because they found out I scored 100% on my relay bashing course at the local training centre. Strange as it may sound, I actually enjoyed doing that, but later got moved onto AN&LCP work (jumper running on the MDF and IDF), which I hated, and why I left
@@simonuden8450 Advice Notes and Local Circuit Provision.... wow haven't remembered those terms for years! lol
So I went on from Strowger and such whilst TTA (they exposed you to a lot of different jobs during the first 2 years) to TXK1 at Brentwood (Essex) plus Locals, then AXE10 out of Chelmsford. Saw my Local Strowger Exch (Rayleigh) changed out to an AXE10 - still got it on video! Enjoyed my time but left with advent of 'Work Force Management' - being driven around by computer tasks, which didn't take into account placement of rivers and your technical ability - that drove me up the wall!! Ended up doing 20.5 years before leaving to go to an OLO.
I can completely understand wanting to get out being stuck on jumper running. Think it was pretty bad for the crews changing out the old Switches, esp. when they knew that when the last ones were done there was no jobs left left for them!
I worked for the phone company in 1970 when this was still in use. The #5 cross-bar (touchtone) was just being tested and put into service, in Los Angeles. and the switchroom was very noisy, with about 20-30 'walls' of these switchers, the film here just shows part of one wall, or rack as they were called.
New guys in the switchroom got a year or two of cleaning and adjusting these things.
I remember doing banks and wipers on Se50 and type 2000 switches back in the early 70s in Telecom Australia. You had a tool that was shipped in a curve to wipe and clean the switches. This brought back many memories.
My father spent 20 years working for Ma Bell, and part of that experience included these kind of switchers. When I was young, he described to me how they worked. But, until this video, I'd never seen them in action. Pretty nifty.
I'd often wondered how the older rotary system worked. That's quite fascinating! (Even for someone born in 1990. 😉)
The engineering skills needed to make this type of equipment were not much different that today. Instead of mechanical design we use digital switches guided by "code" written by equally skilled individuals.
After watching the 1938 and 1969 operator instructional videos it's interesting to see this but what I really want to see is the motions an operator made to change circuits and how easy it might be to mix up with another circuit and how quickly they were expected to find the right circuit.. and how that system works as you're showing here with phone dialing. I remember rotary phones. I was born in 1975. I actually used a rotary phone up until 1993 I believe. From there we quickly got better technology and now alot of homes don't even use phones. The cell phone was slow to start but it's made a huge change to your business I'm sure. At least you guys have a cell service too.. at least last time I checked.
The folks that put these films on UA-cam are the luckiest folks on the planet. I absolutely love this! Wow! I'm duly and truly impressed!!
This equipment WAS reliable. Far more important reasons for replacing it to reduce the number of employees included far lower power requirements, faster processing of calls, and making available features such as caller ID, call forwarding, all waiting, number portability, and many, many other features that we take for granted today. Yes, I also worked in Central offices or many years, on these switches, and also through most all of the later ESS switches, both analog and digital.
Most of the old timers I worked with in the COs were profoundly deaf, and here is the explanation why. I started in the CO, both 5E and DMS and retired from cable repair. The era of fiber switching will be just as revolutionary.
Have you seen Brice Perdue. His chanel shows his work for a small fiber isp. It's cool to see the smalle equipment racks used for fiber optics. PON is an awesome technology
I love old telephone technology. Heck, I love ALL telephone technology. I worked for Bell Labs for about seven years back in the 1980s and got to play with 5 ESS switches, the 3B20D computers that ran them, and learned all about this little thing called Unix. :-) My last two years there I worked on the Autoplex 1000 cellular switch. I was in the lab the day we switched our first call. I'll never forget it. Man, I loved that job. It just wasn't the same after Divestiture. (Boo, Judge Green, boo!!)
True, but it also no longer costs $20 to telephone New York! Too bad the scammers are ruining telephony as we know it.
This certainly brings back memories. I worked for about 2 years doing routines on these. They had to be lubricated and timing adjusted and checked. I wish I had taken a couple of these when we changed to crossbar and then 4e. I helped cut the Dayton Ohio office to 4E.
As an IP networking professional, all these switches and discreet circuits blow me away
My first job, at GTE. Working in a step by step central office from 1968 to '68. This was a real trip down memory lane. Knew those switches well, and all the parts and maintenance routines.
I absolutely love all of the sensations of rotary phones- the look, feel, including the timing and waiting between numbers and sounds are very satisfying for me and I miss my rotary yellow doughnut shaped phone a lot!
If you want one, you can find them on ebay and they will probably still work. I had one that I got a few years ago that somebody had brought to a recycling center. I hooked it up to my home phone line and once in a while I would dial a call on it just for the hell of it. The main thing I liked about it was was the bell ringing the old fashioned way when somebody called me.
Older stuff like this is actually easier to understand and greatly fascinates me
Right now I'm literally sitting in the same room that these or a variant would have been in many years ago. They updated to DMS100 in the 70's ish which is in another room in this building, and it's been running since with zero downtime. It's neat to see this old tech, and how things changed. POTS (and rest of telecommunications really) and everything that goes into making it work is something often taken for granted.
What's in the room, now?
@@TheyRiseBand a desk, a laptop, a printer. basically an office, probably
For our younger viewers, POTS = Plain Old Telephone Service.
I used to be a Coca-Cola delivery man and went into a lot of non-public spaces in the 90's. Some of my favorites were the old Bell South buildings, they were built to be bomb-proof in the 1950's and were just fortresses.
Some of the freight elevators were larger than my first apartment. There would often times be a single rack of equipment in a room the size of a basketball court or larger. Amazing to see how quickly technology progressed.
I repaired home entertainment electronics from 1974 until 2016, so I understand and am amazed by how the POTS twisted pair can carry so much information as a DSL or U-Verse system, giving me telephone, internet, and "cable quality" TV content of 300 channels. I still have U-Verse through an AT&T fiber cable to our house.
I actually have this unit in my workshop at home, Cool Stuff indeed, makes you appreciate the evolution and engineering of the PSTN, i feel honoured to have been given this piece of hardware as a gift from Telstra Staff, due to the mere fact that i showed high interest when attending the telecommunications museum in melbourne.
i still can't believe i own this hardware....... unbeleivable but cool
I love old technologies. Magnificent. Great video.
The Franklin Institute, a science museum in Philadelphia, used to have an exhibit in the 1950s that demonstrated stepper switches, similar to the device shown here. It also had a Univac II computer on display, examples of dozens of clock escapements, a magnetic brake, and lots of other interesting basic technology, in the days when visitors took the time to learn about the exhibits. It had a re-creation of a realistic Nickleodeon, a theatre that showed silent films with a live organ accompaniment, including a roll-down advertising curtain in front of its stage. This theater is long gone. Today, like other science museums, so it can survive, it caters to the current public taste, such as its Space Command exhibit about outer space, and by offering light shows in its Fels Planetarium. Fortunately, it still features a moving 350-ton full-scale steam locomotive indoors.
03-26-2020 watching while covid19 stay@home. Home to see you in 20 yrs.
I love the smell of trichlor in the morning!!
No shit... I have a couple of those metal cans sitting on a shelf in the garage!
ha!
My dad's first job with AT&T in 1947 was as a CO repairman working on these.
I love seeing your old archive footage the work that was done was incredible.
Here is something I tried as a kid and it worked, instead of dialing the number, click the hangup button quickly, like 5 times in a row for a 5, do this for all the numbers with a pause between them and it connects to who your calling normally.
Yes, that was possible as long as your timing was good. Some small retail shops would have phones installed which did not have any "dialing" capability since they just wanted employees to answer the incoming calls and not call out. By pulsing the switchhook, you could make outgoing calls (to the surprise of the store owner).
Digital switching also used this logic.
I saw a similar thing at a museum in Georgia.
It was comprised tall, cylindrical switches.
I was training in the US Army's Signal Corps.
Amazing how far we have come.
Nice to watch these old documantaries. Thanks for uploading.
Absolutely awesome to see and learn the mechanics behind these old switch banks.
This is really cool to see. I have listened to pretty much all of *Evan Doorbell* audio files he hosts on his website but had no clue what the actual vintage SxS equipment looked like.
Beautiful, I really enjoyed this video, thanks for posting it.
Another example of a great accomplishment which happened mostly behind the scenes and which most people never gave a thought to.
My father was the Chief Switching Systems Manager at Michigan Bell in Lansing for many years. I can remember as a young boy going with my father to the office and being amazed at the miles of wires and all those switches stepping through their motions, the sound was mesmerizing. RIP Dad.
I remember a school field trip to a central office in the 50's The clicking noise from all the mechanical switches was deafening..
Beautiful devices, fascinating to watch them in action. The technicians must have been highly skilled to maintain them in perfect working order.
Absolutely amazing. I wasn't expecting this kind of electromechanical complexity. I thought I'd see a bunch of valves (emulating transistors) or something like that.
A fun step back in my life. When I was getting out of the Army from my first enlistment, I signed up for a course called Project Transition, to prepare me for a job in the real world. Well I always had a deep interest in radios and telephone so I took a course in telephone central office repair. What it amounted to was to intern with the engineer who operated the switching central for William Beaumont Army Hospital, a brand new building (in 1972) with a brand new switching central that looked exactly like the one in this film, and operated the same as well. I learned a lot from that course, and I was all ready to go to work in a central office, when my wife found an add for police officer in my home town. The add said "MUST BE A VIETNAM VETERAN!" well I qualified for that requirement, so I sent in an application. I never heard back from the City, so I figured I was not chosen, the only reason I even thought about it was that my brother-in-law was a cop and I really respected him for his dedication. So I get home from the Army, having driven from Fort Bliss Texas to South Dakota, and I am home for exactly 6 hours when the phone rings, it is the town mayor, who asks me where the hell I have been, well I told him on the road, seems they had been trying to call me, I was the only Vietnam vet who applied, and they had this grant that would pay my wages for six months so long as they hired me for a guaranteed 1 year, but I needed to be sworn in on that very day. So it was I began my career as a police officer riding along with an officer who would turn out to be the Chief about three years down the pike in blue jeans and a police jacket, with a pistol on a holster hooked to my old cowboy belt.
Seeing slo-mo done in the fifties really has its own vibe. Love it
So much work went into these systems. Amazing that they got reliability.
Detroit8V92tta - Not that amazing. They were built for long-term reliability because otherwise the maintenance costs would have been too high. Today, we get the impression that mechanical systems are unreliable because so much of what we buy is junk. It doesn’t have to be that way, but you have to be willing to pay for a better machine.
I worked on this starting in 79, also Strowger rotary exchanges from the 30s. In early 80s we switched to NC400 crossbar but nobody understood them so they were quickly changed to solid state. I still have fond memories of maintaining step by step and even oiling the tone generator.
Dr. Stroeger, a dentist was the inventor of the step by step switch. The patents for it were actually held by AUTOMATIC ELECTRIC, the development and manufacturing arm of General Telephone (GTE).. while BELL LABS and Western Electric with the development and manufacturing arms of the Bell Telephone system. The work at BELL LABS is directly responsible for the digital world we now live in.
Early in my career i used to work on this equipment. Miss those days
When I was young I used to practice using the cradle buttons to send the pulses to the system instead of the dial. the buttons had to be clicked down at a steady rate in order to complete the call.
Ahh ! The sweet sound of a line finder, selector and connected !
I today (February 2017) working on this kind of headquarters, you might think it's impossible, but it really is true. I live in Serbia.
Frederick Orestuk I worked on first floor of CO, when the local switches got real busy I would step outside to see what people were calling about. Useally snow or rain was happening. Could tell when school was out by switch noise too.
Nostalgia. I started working in the telephone industry when many SxS switches were still in service. I went to work for Northern Telecom (Nortel) in the '80's selling DMS-10's & DMS-100's to independent telcos. Made a damn good living replacing these switches with DMS digital switches, which of course are now obsolete in their own right with many of them being replaced by IP based softswitches.
I freaking love this! Love love love electromechanical switching. I have old traffic light control boxes made by Crouse-Hinds That advance the traffic signals in virtually the same way.
I remember when you could dial your own number, get a busy signal, and talk to other people through the busy signal!
Good service is something companies have now clue about no days. Good in general is something most people don't know much about now that I mention it.
this brings back memories, I use to work o these types of switches back in the seventies when it was being replaced by digital systems.
So much time must have gone into the machining of all that equipment.
I was just thinking the same thing!
Suitable jobs in making and reconditioning telecom gear were held by persons we would now call disabled. AT&T policy was great in its day.
T mobile still uses these to this day.
True. Their service is complete shithole
Lmfao
T-Mo at my home is two bars more signal than AT&T. Glad I switched months ago. Should have done it years ago.
@@stephenarling1667 Almost like cell service of a carrier varies across different parts of the country.
@@sean8102
Of course it varies, even over the span of a few city blocks. I merely said T-Mo has shown its coverage and speeds superior in the same areas of my town where I used to use AT&T.
This is the best explanation that I have seen.
I worked with this type of office. “ Bank n wipers” we use to say cus you would spend most of your time on maintenance of these switch selectors.
It's remarkable it worked at all when you consider the mechanical switches and the sheer number of punchdown connections between each phone, the nearest CO and then to the phone on the other end.
It worked very well indeed. Western Electric were fanatical about reliability.
Great video, yes this equipment was. Very reliable, I remember endless rows of these switches.
Incidentally I thought they were called STROWGER SWITCHES.
Almon Bl Strowger invented the SXS switch, and Automatic Electric manufactured the Strowger SXS switching systems for many years. Then there was Stromberg-Carlson XY, Western Electric 04, Panel, Nbr 1 and Nbr 5 crossbar...those were the days, for sure.
Good old stuff,it was great making these things in my youth,the factory was nearly 3000 girls strong, us apprentices were kept busy!!!
I work in VoIP, practically doing all these same things via servers. The transformation from networks and switches like these to the internet tech we have now is hard to imagine.
Wonderful film. Thank you for sharing.
Don't just write this kind of thing off as "old". You really have to respect the precision work of engineers that made it possible given the state of technology in their day. The principles that it runs on are just as valid today. Technology doesn't become obsolete, it's rather the *products* of technology that supersede each other. Technology isn't a physical thing. It's the study of techniques as they relate to fabrication.
❤
These were called Strowagwer switches, named after their inventor, who happened to be an undertaker. Later on, many of these were replaced by a later type of electromechanical switches called crossbar switches, which were more efficient and less prone to problems. All were of course in more recent times replaced by electronic equivalents with no moving parts.
The name's Strowger. Almon Strowger. :)
"Do you expect me to talk?"
"No, Mr Strowger! I expect you to dial!" :D
Sorry I messed up the spelling. I stand corrected, it’s Strowger.
@@DancingNotes83 And I updated my original comment since I think I came across as a bit too serious. :)
I remember watching a Step Switch in the early 80s at a Military Base. they did had the SL and SP Switches too, but part was still Step, a few years later it was mostly DMS
It is interesting that despite AT and T developing more 'high tech' systems such as 'rotary' (used in New Zealand and Europe, 'panel' (a development of rotary used in NY etc) and crossbar, it used the 'step by step' switches for smaller offices. The British Post Office considered purchasing panel switches for London but instead used step-by-step with 'directors' to translate the thirst three digits of the dialled number. Directors were not used for large Australian cities such a Sydney or Melbourne, instead they used 'discriminating' selectors at sub-main offices and 'trumbone' connections for satellite offices. This was not as scaleable as 'director' so crossbar was overlaid. This showed step by step was scaleable up to very large networks and was not knocked completely off the perch until electronic switching became feasible.
Interestingly Keith 'plunger' linefinders (possibly 1915 vintage) were in use in Whanganui New Zealand up to the 1990's and some of these linefinders are now on display in the Science Museum in London. That office would have used more recent step by step equipment as well integrated with the early Keith step by step equipment. In NZ very little electromechanical equipment was scrapped until electronic switching became economic. In one town the rotary equipment had been there for 60 years and the suppliers of the electronic equipment were jokingly asked if they would guarantee their equipment for 60 years.