First call between Panel and Crossbar offices
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- Опубликовано: 16 сен 2024
- This video is of the first call between our Panel and No. 1 Crossbar switches. The last time these machines were able to communicate with each other was 1974, when the Panel switch was finally decommissioned.
We did not expect this to happen today, so the video is very impromptu. Would have liked to use lav mics to capture the dialogue over the phone, but there simply wasn't any time, since we were so excited about this.
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It is my great pleasure to announce that today we made the first successful call from the Panel office to the No. 1 Crossbar!
This is a truly momentous occasion! The museum has the only remaining Panel and No. 1 Crossbar switches left in the world, and for them to once again connect calls to each other after more than 40 years is an incredible achievement!
Our Panel switch, "Rainier" served the Columbia City, and Rainier Valley neighborhoods of Seattle from the Parkway central office on Rainier Avenue, from 1923 to its replacement in 1974. The No. 1 Crossbar, "Vernon 2", served the University District from the Lakeview central office on 65th from 1942 until its replacement in the early 1980's. During their time in service, they interoperated with each other, and with the many other central offices in the city of Seattle.
After they were brought to the museum in the 1980s, communication between the two machines was never established, because the terminating senders that the "Vernon" Crossbar required to complete calls from the "Parkway" Panel office were no longer available. This has been the case ever since the museum first opened.
Last year, we were able to locate a fellow collector who had the exact parts we needed to re-establish a connection between the two machines. He helped decommission many electromechanical COs in the 1980s, and had several revertive-pulse terminating senders that he brought home from an office in Brooklyn, NY. When he heard about our machines, he enthusiastically agreed to donate the equipment we needed.
After we retrieved the units from Connecticut, a team of volunteers, young and old, spent the last year wiring and installing them in our "Vernon" Crossbar office. It was a fantastic learning process, and we have grown together as a team during this time. I'm proud of the work we've done together, and completely humbled by the time and energy that everyone put into this project.
I had that same reaction after I finally managed to get Asterisk to register and connect the phones on my home pbx... Only your system is MUCH cooler! Congrats! ^_^
Oh, me too :D And when I managed to change the ringout tone, I was sooo happy! :D
Although no one in my house uses ground lines or even the intercom in the house any more. I still get a kick out of having SIP trunks to my Asterisk, then H323 to My AVAYA IP Office that then connect H323 to my Nortel Norstar that finally ring my analog 1940 era desk phone.
Congratulations on the successful first call! I know a lot of hard work went into getting the two switches talking to each other.
I once worked at the Dupont Panel Central Office switch in Washington D.C.. The switch was decommissioned in 1972.
I am watching these videos and learning so much, and am just fascinated and awed by the knowledge and dedication to the technology and history!! Well done all!
Sarah, you are a treasure, as I am sure all the other volunteers who got the terminating RP sender working in the #1 crossbar are as well. Thanks for all these videos. And congratulations on getting the panel and crossbar #1 talking to each other.
Back in the 1990's I worked for an independent cell phone carrier, and I remember when I got our first SS7 trunk group up and working how excited I was....finally caller-ID! Before SS7 we sent and received calls with MF signaling (and we even had two small trunk groups with dial pulse, basically they were DID trunk groups) and had no caller-ID. It took a lot of configuration to get all the SS7 data fill in the Nortel DMS-MTX switch, and to set up the 56 kbs A-Links for the SS7 data connections. But yours was a lot of wiring, not data fill, right?
(A DMS-MTX is basically a DMS 100 without all the line equipment, and besides the telephony software also has the software to control the cell sites too.)
You asked for suggestions for future videos, so I have two:
1. Could you one day go through and explain how the panel office sender works in more detail, and how it communicates with the decoder to get the trunk routing?
2. And a basic discussion of how the panel switch came to be might be interesting.
A while ago I came across an old document on-line (cannot remember the web site now) that described the original panel installation in Omaha. It was basically a maintenance manual and had a lot of schematics of the various parts of the entire installation. As I remember that office did not originally use a line finder frame; as I remember the L relay was wired to some rotary switches to connect to the district frame??
I pretty much read the entire document and I understand the basic theory of how the linefinder and district frames replace the manual A board, and how the incoming and final frames replace the manual B board, and the fact that a subscriber's line had to be wired to both the linefinder and the final frame, the purpose of the L and cutoff relay, etc, but a discussion of that would also be helpful for people who do not know all that, and would l think make it easier to understand why panel switch is designed the way it is designed!
I also find it interesting, if I understand correctly, how the office frame could sort of serve as a sort of mini tandem switch in larger panel implementations before the crossbar tandem switch came to be, so a discussion of that might be interesting for the people that are following your videos.
A little on my experiences with connections between crossbar and panel:
I grew up in the Washington DC area, and moved to Bethesda in 1951. Our phone was served from the
OLiver office in downtown Bethesda on Wisconsin Ave. in a magnificent old stone edifice and later in 1959 we moved out further to North Bethesda. When we moved we kept the same phone number but in the early 1960's TPC built a new CO closer to our house and we were connected to the new EMpire 5 CO at that time.
I know EM 5 was a crossbar #5 office out on Bradley Blvd (and this building also served the AXminster 9 office that was for Potomac, MD, (actually I think it was the same crossbar switch, you could dial our number with the AX9 or EM5 prefix if I remember correctly), and as mentioned above OL4 was in downtown Bethesda. After conversion to 7 digit dialing, they added OL2 and OL6 at the downtown Bethesda central office (probably crossbar) but our phone was on the original OLiver exchange which was a panel office, and my dad's office in downtown Washington had FEderal 7 and EXecutive 9 numbers. FE7 and EX9 were downtown Washington business district central offices. I believe these offices were also old panel offices, because when calling them from our home EM5 number I would hear the unique sounds of revertive pulsing.
Most of my memories of phoning were from the time we were on the EM5 crossbar #5 office. If calling out of our local exchange to a panel office I seem to remember first hearing MF, and then I would hear revertive pulsing.
I believe the EM5 office was first sending the call to a tandem. I don't remember if I would always hear MF, but I do remember hearing MF a lot, and then RP. Perhaps the EM5 #5 crossbar office could not send RP and had to send MF to the tandem to be able to connect a call to a panel office???? Or perhaps #5 crossbar could connect directly to a panel office, but it was more economical for TPC to send the calls through a tandem office due to the large number of different exchanges it was not practical to have direct trunks from the suburban office to those central offices?
(In our cell phone network, almost all calls were sent through the Bell tandem which was a DMS 100/200 switch. But as the network grew, we got direct trunks several end offices where we had high amounts of traffic. Some of the trunk groups had several hundred trunks.)
Also, I believe, but do not know for sure, that all this was on voice frequency wire pairs, no carrier. Well, I do know the trunks coming in and out of a panel office were wire trunks as the RP signaling had to be on a trunk with DC continuity, but not for sure if the trunks to and from our crossbar office were wire but I suspect they were wire to the tandem office that the EM5 crossbar was connected.
Just some memories of when panel was still widely used from the first 25 years of my life.
Again, thanks, Sarah, for all you are doing. Oh, I have one more question if you don't mind answering: are you a paid staff of the museum or volunteer? You seem to spend a lot of time at the museum!
Thanks, and take care.
Hey Eric, sorry for my late reply. Was on vacation :)
Good job on getting that SS7 trunk group going. Yes, its always super exciting to finally solve. a problem that you've been working on for a while!
Yeah, the job was a lot of wiring. The senders were damaged in various ways during removal, and there were parts missing here and there. The difficulty was compounded by us not having ever seen a working sender of this type before. We had schematics and everything, but we didn't have any idea what it was supposed to look & sound like when it was working "right". So it took us a while to reverse engineer it and figure out what it should be doing.
One day shortly after we got the senders working the first time, it just stopped. It almost worked some times, and failed immediately other times. The failure was inconsistent, except that it always failed, just at different moments. We went through everything, checking voltage values, burnishing relays, taking slo-mo video to try and figure out the order of operation. All in all we spent almost 2 years on and off trying to make it work, but no matter what, we couldn't find the problem. Well one day, Astrid decided to start hitting the relays with a small hammer. Nothing rough, just enough to give it a moderate tap. She hit a relay, and then all of the sudden, it worked! By tapping each relay in the sender, we were able to narrow the problem down to a 2x2 inch block of space where hitting it there made it work every time. I carefully investigated the relay, and found a tiny blob of solder hiding way in the back of the relay in a place that could only be seen with a dental mirror. There's no way we would have ever though to look there. I popped off the solder and its worked perfectly ever since!
I'm always looking for new video ideas. I'd like to publish videos that people enjoy, so I'll
put those two on my list!
You're correct about the panel switch in Omaha. Each subscriber line had its own rotary selector, and on the banks were all of the different district selectors that it could choose. It would spin until it found an available district out of a choice of 22. (That's the number of positions on those rotary selectors). This was bad for a couple of reasons. First, giving every subscriber their own rotary selector was expensive, and second, only having 22 districts to choose from was not very efficient. Even if an office had 600 district selectors, each line could only ever choose from 22 of them. Our panel office at the museum was the first one outfitted with line finders from day 1. All of the panel offices before it originally had line switches, and were later upgraded with line finders. This makes our line finder a "version 1.0" kind of thing. They were later redesigned, and the newer type were installed in all panel offices after 1926. Also good idea about explaining how the panel replicates the A and B boards of a manual office. That's something I like to talk about on tours, but I've never gotten around to explaining it in a video! Also spot on about the office frame. It was optional in panel offices. Ours didn't get outfitted with them until the 1930s, when the trunking plan became large enough to warrant them. We use the office frame as a mini tandem for the 1XB as well. The 1XB will first try a direct route to the other switches, and if it is unsuccessful, it will choose an alternate
route through our office frame--just like a tandem, except that its in the same building, just across the room.
It's believeable that the 5XB office couldn't directly RP to the panel offices in DC. In Seatt
le, once the panels started aging, they started sending traffic to and from the panel offices
through the big tandems here: East, Mutual, and Emerson. That way, they didn't have to equip a
ll of the 5XBs with RP senders and registers, which took up space in the office. And in an out
lying suburban office, its no surprise that calls to the big city panels would all filter thro
ugh a tandem. NYC was like this also, for trunks to NJ and CT.
Oh yeah, at the museum we are all volunteers. I have a day job, but I prefer not to talk about
it. It pays the bills, and gives me the time I need to do the things I really care about. Tha
t is enough compensation for me :)
@@ConnectionsMuseum Sarah, thanks for your response/comments/clarifications. If I ever get out west again I will have to set up a time to visit the museum again (I visited it in the late 90's or very early 2000's). Keep up the good work and I will keep watching any new videos you make. BTW, besides your good works on the switches, you do great video editing too!
Does anyone remember the old (circa '60s, '70s) n-1-1 codes? When I was working as 1XB switchman, I knew them, but all I think I remember are 3-1-1 as installer's ring back, 4-1-1 as information ('directory assistance'), 6-1-1 as repair service and 9-1-1 as emergency, of course.. Sure would enjoy having the whole list again.
I would have picked up the phone answering, "What are you wearing?"
In the little boxes in my mind that things get sorted into, there is one that Astrid goes into along with Anne Hathaway...
Looks like a #1 XB revertive pulse sender. Am I correct? I wish the museum was near me on the East Coast
Yup!
ohai astrid
Follow-up on n-1-1 codes. Of course 2-1-1 was 'long distance'. That only leaves 5, 7 and 8. Any takers?
transsisters or vacuum state?
Did you send Dial Pulse or MF between the two offices? Can the 1XB make Trunk to Trunk Calls?
Neither! We sent revertive pulse between the two offices. That's the only signalling method the panel switch can use (other than PCI). The 1XB can't do trunk->trunk calls, but we do have an XBT marker sitting in there, so if we do enough haywiring, maybe ;)
Thank You for the information. We never had 1XB in Oklahoma. I served as a SXS switchman (Switching Equipment Technician) from 1971 to 1976. I was a 1ESS and 1AESS SET from 1976 to 2000. From 2000 to 2012 I worked DMS100 and 5ESS. Thru It all I worked on Transmission Equipment, T1 carrier, D1B D3 D4 & D5 Channel banks. DCS and some stuff I can't remember the name of. I hope to some day get to the Museum. Thank You Very Much.
Can we dial in from outside?
@@MichaelWallace-oq3wd What is the number for the gateway?
@@MichaelWallace-oq3wd No, not familiar with that!
@@MichaelWallace-oq3wd I installed discord!
@@MichaelWallace-oq3wd Yes
@@MichaelWallace-oq3wd Don't have your email address!!