Well, I'm happy to be of service and thanks for watching.

@@Hicken65 yes this is the only video I've found that explains it, thanks so much. It's such an interesting system

@@michaeljones5681 Well this 551A PBX is the most basic of switchboards. The telephone company toll switchboards were much more complex and interesting. If you're curious to see how operators processed long distance calls to and from payphones, look for my video "The 3-Slot Payphone Part 1". Just search my channel name, Hicken65, on You Tube. Thanks for watching.

You're welcome and thanks for watching.

Well, I'm always happy when my videos help recall fond memories. Thanks for watching.

I always enjoy receiving anecdotal comments like yours. Thanks for watching.

Well, I'm glad you found it informative, and thanks for watching.

Yes, this certainly is the most basic of the PBX switchboards, but it was quite popular and served its purpose. Thanks for watching.

Well I appreciate your kind words and thanks for watching.

Yes, those truly were the good old days. Seeing a cord switchboard in operation brings back fond memories for many people.

I worked in the 1950's at the GPO Switchboard near Goodge St. London.

I worked in the 1950's also at the GPO near Goodge St. London

Thank you. I'm glad you enjoyed it.

People like you make all my efforts worthwhile.Thanks for watching.

These boards were ubiquitous in their day. Thanks for watching.

Well, thank you for the compliments and for watching.

Enjoy your visit and thanks for watching.

You're welcome and thanks for watching.

You're very welcome and thanks for watching.

Well, I very much appreciate your comments and thanks for watching.

You're welcome. I always enjoy getting responses from fellow switch techs. Thanks for watching.

Well, thank you very much and thanks for watching. If you are interested, you may want to check out my other telephony videos. Just search my channel name, Hicken65, on You tube.

You're welcome and thanks for watching.

It would be great if you could video the intricate workings of a jukebox and put it on You Tube.

Well, as you saw on the Crown, placing a call to the Queen was much more complicated than merely patching through a PBX switchboard. But I'm glad my video was helpful to you. Thanks for watching.

Well, I'm glad you found it too. Thanks for watching.

Too slow. He puts me to sleep. And why not just use his finger to indicate? That pointer seems a bit much.

Glad to help. Thanks for watching.

Just cleaning up its appearance makes it a classy looking antique. If it's a hobby you enjoy, a full restoration to working order takes a lot of time and effort, but the results are quite rewarding. Thanks for watching.

You're welcome and thanks for watching.

Well, you are most welcome. Good luck with your project and thanks for watching.

Glad you enjoyed it and thanks for watching.

@@Hicken65, my mother was an operator all her life and I relived all those experiences as a child when I visit her at work and now, thanks to you I know how the switchboard operates. Thank you once again for bringing back all those memories!

You're welcome and thanks for watching.

Well I'm glad I was able to satisfy your thirst for knowledge. You might also like my videos on rotary dial switching equipment. Some are very long and detailed and some are reasonably short. Just search my channel name "Hicken65" on You Tube. Thanks for watching.

It's always great to receive interesting anecdotes about this old equipment. Thanks for watching.

In working condition, these boards are a joy to demonstrate, especially if it's a hands-on demo for kids. Your setup would have been an impressive sight with those phones. Thanks for watching.

That's the beauty if this switchboard . For any business, any employee could be trained to use it in just a few minutes. In addition, the operating instruction are posted on the board.

Well, I'm glad I was able to solve the mystery for you. Thanks for watching.

Well, I'm happy that my video met your expectations. Thank you for your kind words and thanks for watching.

You're welcome and thanks for watching.

I think you would really have enjoyed working on the old long distance cord switchboards, in particular the type 3CL. They were much more complex than the 551A PBX, but lots of interesting different tasks to perform.

You're welcome and thanks for watching.

I started working for a telephone company when I was a teenager and it was the era of cord switchboards and electromechanical automatic switching systems. I worked in a central office troubleshooting and maintaining all this equipment. I have nothing but fond memories of those days. Thanks for watching.

You're welcome and thanks for watching.

Well, that's pretty late in the game for this board, but I imagine a few lasted into the 1980's. Thanks for watching.

I also remember that the TV used to go off the air overnight. When it came on in the morning , it displayed a patterned test card that allowed you to adjust the vertical and horizontal alignment of your picture (after your tubes had fully warmed up, of course). I'm glad you enjoyed the video. Thanks for watching.

Glad you enjoyed the video. You're absolutely right, of course, about the word "attendant". I just felt the word "operator" was more in tune with what people would recognize as the name for the job, regardless of whether the switchboard was located in a PBX or in a Telco central office.

In a single position PBX switchboard setup, when an operator is attempting to complete a call to a PBX station, she/he can tell if the called line is busy by looking at its jack. If the jack has a plug in it , it is in use. If it doesn't have a plug in it, it is idle. In a multiple position PBX switchboard set up, the PBX line jacks are multipled to each position. An operator can't tell if a line is in use just by looking at its jack, since the line may have a plug in its jack at any other position in the multiple lineup. If the line is in use, tapping the sleeve of the line jack with the tip of a cord plug with its associated talk key operated will cause clicks to be heard in the operator's headset.

Hicken65 I thank You for Your time :-)

@@duomaxwell1210 You're welcome.

Your English is fantastic, never apologise! I'm a Brit and I understood every word you wrote. :-)

As you might imagine, back in the day, large businesses with thousands of telephones would have very extensive switchboard lineups. Thanks for watching.

You're welcome and thanks for watching.

The male operators were mostly teenage boys, who proved to be too rude, rowdy and obnoxious for the job. Thanks for watching.

@@Hicken65 Teenage boys, rowdy and obnoxious, never heard of such a thing.

Yes, this is true. I did address this issue in a reply to another commenter (duo maxwell) about a year ago.

Hicken65, I used to work for AT&T as a telephone operator 20+ years ago. The cord switch board had already been phased out and we were using computer terminals to help customers complete their calls. I wish I had worked using a cord switch board like this one. I've always been fascinated by them. Thanks for the video and for your reply.

I'm not sure I understand what you're asking, but I'll give it my best shot. PBX's , or Private Branch Exchanges, are telephone switching systems for businesses.They can be very small, like the one in this video, or be very large, large enough to handle several thousand employees in a business. If a business has more than one location, it can have a PBX at each site. These PBX's can be joined together by tie trunks, which handle the calls between the PBX's. The telephone network that the general public uses is called the Public Switched Telephone Network (PSTN).The switching equipment units for the PSTN are located in telephone company buildings called central offices. Small to medium sized towns would have only one central office. Larger towns would have two or three and cities would have several to dozens. Generally, all the CO's in a town or small city would be linked together with direct point to point local trunks. Larger cities would require one or more tandem switching central offices. With the tandem arrangement, the local trunks from the CO's would be wired to the tandem CO.The tandem CO would simply switch incoming trunk calls to outgoing trunks. I hope that answers you're questions. Thanks for watching.You may be interested in my other telephony videos. Just search my channel name, Hicken65, on You Tube.

A PBX would only be used in a private business with many phone stations, like an office or a hotel where each room or desk has its own phone. That's why its called a Private Branch Exchange. The trunks are outgoing lines. The 15 holes in this case (maximum of 40) are the internal phones. The operator can connect any of the 15 phones to each other if one desk wanted to talk to another desk or the operator could connect up to 6 of the 15 to an outside line by connecting them to one of the trunk lines.

You're welcome and thanks for watching.

Well, thank you. I do have several videos on Strowger. Just search my channel name, Hicken65, on You Tube. Thanks for watching.

Question #1 If the rear key is operated to the ringing position, the station connected to the rear cord will hear audible ringing tone through their receiver, but it is somewhat louder than audible ringing heard on a normal telephone call. The station connected to the front cord will just hear a click when the rear key is first operated to the ringing position. This situation is, of course, reversed when the front key is operated to the ringing position. Question #2 If the the front keys of more than one cord position are in the operator's TALK position (back), then all stations connected to these cord positions can communicate with each other. Thanks for watching.

Glad you enjoyed it and thanks for watching.

While watching this video intently I felt I was back in the 30s and therefore I had to laugh when I saw that futuristic Jetsons device sitting on the right lower corner of the switchboard desk. And it was wierd when a call was placed through the board to that "miniature telephone of the future."

Only one DC battery supply is required for talking and relay operation, but it is 24 volts instead of 48. Certain old telephone key system power supplies work well for this switchboard application, such as the Western Electric 20B2 that I am using. It supplies both the DC voltage and the AC ringing voltage. There is one currently available on Ebay, but they are asking about $150.00. Power is connected to terminals on the MISC Terminal Strip. On mine, the negative 24 volt battery is connected to terminal 1; the positive ground is connected to terminal 45; the AC ringing generator +/- is connected to terminal 27 and the generator return is connected to terminal 35. The trunk circuit tip and ring wires connect directly to the 2 wires of my residence landline, which is a regular loop start line. You are correct on your procedures for the two types of calls. The internal wiring of the cord circuit is not exactly the same for the front and rear cords. I believes some supervisory functionality may be lost if a rear cord is plugged into a trunk circuit. I can send you a photo of a copy of the printed card instructions that I found in one of the switchboard Equipment Drawings. Just post your email address in a reply to this comment. On an incoming call, the trunk is seized by the far end Central Office when it completes its connection to the switchboard telephone number and sends ringing current towards the switchboard. The seizure is indicated to the operator by the lighting of the trunk lamp. When the font cord is plugged into the trunk, it stops the ringing from the Central Office. Pushing the front cord key to the TALK position establishes the talk path. The operator is instructed to push this key before plugging into the trunk to avoid any "dead" air to the caller. The telephone stations are wired with their ringers bridged across the tip and ring wires in the same manner as single party residence telephone sets. I'm not sure if that's what you meant by "bridged ringing". I hope this answers your questions satisfactorily. Good luck with your project and thanks for watching.

@Larry Butler They were not the same color, perhaps they seemed like on your end screen but, they weren't.

Next time I need to do some maintenance in the back of the board I'll take a picture, but i don't think my existing camera would produce a high enough resolution for what you're looking for.

No, there is no lamp signal for this condition.

This switchboard was not a telephone company switchboard that served residences and businesses directly as part of the Public Switched Telephone Network (PSTN). Instead, it was designed to work as a Private Branch Exchange (PBX) to serve small businesses that required 40 or less telephone sets to run their businesses. For example, a business with up to 40 employee work stations in an office building, or a motel with up to 40 guest rooms. Incoming calls from the PSTN or outgoing calls to the PSTN were handled by two way trunks that connected the switchboard to the PSTN. These trunks were located on the bottom row of jacks on the switchboard and are shown in the video. I hope this answers your query. Thanks for watching.

I'm glad the video rekindled some good memories for you. Unfortunately, I don't have any of the other apparatus you mentioned. I imagine those items would bring back both some good and some frustrating memories.

Me too, Susan! Early 70's. But it wasn't exactly like this one. It's been over almost 50 years ago. Hard to remember exactly what it was like, but it seems the cords on my PBX were side by side. And there were buttons to push instead of the levers to make extension phones ring. I also remember the wax stencil duplicator, but I don't remember ever operating it. Just seen it done. (Edit - Oh, just saw below that it was probably a 555 that I worked on.)

Just search on "Ernestine" in KZfaq and a number of the Lily Tomlin videos will show up. You can get a good look at her 555 switchboard with its side by side cords.

I think you are having some confusion regarding the key rows. The row closest to the operator is the front row and the row closest to the vertical face panel of the switchboard is the back row. The operator always pushes the front key backwards to its locking position to talk to a subscriber. An incoming trunk call is answered by inserting a front cord into a trunk jack and pushing back on the front key to enable the operator to talk to the incoming caller. The back row cord is plugged into the called station jack and the back row key is pulled forward to ring the called station on this incoming call. On a station to station call, the front key of the cord circuit is pulled forward to ring the called station (see starting at 29:28 on the video). On a connected call, if the operator pushes back on the front talk key, there will always be a 3-way conversation. Splitting was available on many types of switchboards, but not the 551A. I hope this answers your questions and thanks for watching.

@@Hicken65 It does, thank you. It is the case of an incoming trunk call that once connected to the station, the back key is pulled in order to ring the station. That makes sense. Again, very interesting. I saw another video where there was a challenge to a board operator to handle multiple calls as fast as he could. It was great to watch! There is a movie on Amazon Prime, "The Vast of the Night." I was so-so on the movie, but there was quite a bit of manual switchboard stuff going on. I noted that once the called station was connected by cord, the ringing was done by the attendant pushing one button, and then she just flipped a lever up to disconnect her voice from the line. She moved on to the next call. Apparently, the ringing was automatic after that. Thanks, again! Chuck Gage

@@cggage Glad to be of help. I have a number of other telephony videos that you may be interested in. Just search my channel name, Hicken65, on You Tube.

It's always nice to hear that another cord switchboard has survived. Thanks for watching.

This is generally done when the existing phone call is about to be terminated but one of the parties wants to be reconnected to a new party.

Every PBX cord switchboard had a design capacity that defined the maximum number of telephone jacks it could terminate. On my 551A switchboard, that number was 40 jacks, but PBX switchboard designs ran all the way up to several thousand jacks to satisfy the requirements of large businesses. When several hundred or more jacks were required, one operator would not be able to handle the traffic without severe delays, so the jacks were multipled to as many switchboards needed to handle the load. So, for example, a business with 3000 telephone extensions may have had 10 switchboards, each with 3000 jacks wired in parallel across the 10 boards, serving the same 3000 telephones, but with 10 operators handling the load. Some businesses had more than one geographical site in a city, and each site would have its own switchboard(s) and telephones. There would be trunks between the switchboards at each site to establish connections between the telephones at any of the sites. Sometimes, a business with only one switchboard would outgrow its capacity and add a second one to handle the growth. In such cases, there would be trunks between the two switchboards to handle the calls from telephones on one switchboard to telephones on the other switchboard.

Well switchboards and automatic telephone switching systems could get overloaded very quickly whenever some local or national emergency or significant breaking news event was occurring.

Both the ringing current and battery were usually provided over cable pairs from the telco central office. This supply was not affected by a local utility power failure. However, the battery supply may not have been adequate for PBX's that had a long loop to the central office, and so a local battery was provided, generally locally charged through a rectifier. If the supply from the central office was disrupted, the local battery would handle everything but the ringing, which was handled by the manually operated magneto. Of course, a cable disruption would also affect the ability to handle incoming and outgoing calls.

@@Hicken65 that's some interesting insight, thank you. the phone companies are in the business of communication, not so much power distribution. that's a job for the utility company. makes sense. things like that are still done today. land lines are slowly going away, but in coming years we'll see more and more power over ethernet (PoE). you have a central switch in the building that provides power to devices over the communication lines. it kinda scares me, how much power the new tech tries to push over a wire that was only intended for communication. these wires are thin today. were the telephone wires back then all copper?

@@lorenzo42p Yes. The cables from subscribers premises to the central office are twisted pair copper, typically in 22 to 26 wire gauge depending on distance from the CO.

No, there are no disconnect signals provided by the trunk circuits. The PBX operator will only be aware of a disconnected call when the supervisory lamp associated with the PBX station lights up when that station hangs up the phone.

Thank you and thanks for watching. There is a wiring diagram on the Telephone Collectors International website. Here is the location. www.telephonecollectors.info/index.php/browse/bc-switching-library/all-bc-library-topics/western-electric/12289-weco-551-a-551-b-pbx-swbds-wiring

@@Hicken65 Thanks. Maybe they can help me identify the phones I found too (non-bell system).

@@JohnOverstreet There is a wealth of information on the TCI site and they also have an email group for any questions you may have. If you are interested in vintage telephony I would encourage you to join this organization.

You're welcome. The lights that come on during all call types are displayed beginning at the 27:00 minute mark. Thanks for watching.

No. It hasn't been a problem at all.

Don't be a troll and prank call him now, LOL. Just kidding.

The operator would say something like "All circuits are busy; may I call you when one becomes available?"

@@miata149 well, not exactly...the attendant wouldn't have a circuit to connect to the station or trunk. The outside line would ring till they hung up or the station would get tired of waiting and hang up. :)

a light will turn on. Basically, if the operator needs to do anything there is a light. If everyone is connected then there are no lights. That's what I understood.

Yes I did. I had the good fortune to get "hands on" with manual switchboards, SXS and crossbar switching equipment.

Consider yourself fully trained. You'll still have to wait for the time machine. Thanks for watching.

Crobertg10, You don't have to go all the way to the 30's, just back it up to 1980 I was working back then on " cordboards " until 1992 we got the last cordboard removed and went on to D.I.D. phone service. I must tell you that I miss the cordboard, imagine having them since 1952 until 1992 that was the longest relationship my boss ever had. Good memories !

The connection to the 551A is via the MISC Terminal Strip in the back of the unit. The particular terminals to connect is variable based on the options installed. On mine, the negative 24 volt battery is connected to terminal 1; the positive ground is connected to terminal 45; the AC ringing generator is connected to terminal 27 and the generator return is connected to terminal 35.

@@Hicken65 thanks very much!