Retrotechtacular: Cut All the Cables in this Speedy Teleco Switch Upgrade

In this short but intense classic of corporate cinematography, we get to watch as the Pacific Bell central office in Glendale, California is converted to electronic switching in a 47-second frenzy of cable cutting in 1984.

In the 1970s and 1980s, conversion of telephone central office (CO) switch gear from older technologies such as crossbar (XBar) switches or step-by-step (SxS) gear to electronic switching systems (ESS) was proceeding apace. Early versions of ESS were rolling out as early as the 1950s, but telcos were conservative entities that were slow to adopt change and even slower to make changes that might result in service outages. So when the time finally came for the 35,000 line Glendale CO to cutover from their aging SxS gear to ESS, Pacific Bell retained Western Electric for their “Speedy Cutover Service.”

Designed to reduce the network outage time to a minimum, cuts like these were intricately planned and rehearsed. Prep teams of technicians marked the cables to be cut and positioned them for easy access by the cutters. For this cut, scaffolding was assembled to support two tiers of cutters. It looks like the tall guys got the upper deck, and the shorter techs – with hard hats – worked under them.

At 11PM on this cut night, an emergency coordinator verified that no emergency calls were in progress, and the cut began. In an intense burst of activity, each of the 54 technicians cut about 20 cables. Smiles widened as the cut accelerated, and sparks actually flew at the 35.7 second mark. When done, each tech turned around and knelt down so the supervisors knew when everyone was done. At least one tech couldn’t help but whoop it up when the cut was done. Who could blame him? It must have been a blast.

60 thoughts on “Retrotechtacular: Cut All the Cables in this Speedy Teleco Switch Upgrade

        1. If the distribution frames are designed and installed correctly, then they are ready to support what is called Dual-Feed-and-Transfer (DF&T). Banks of channels are moved and tested one at a time at minimum traffic hour periods over a period of time so as to minimize disruption and ensure the quality of the circuits. What’s being described here is an abomination of poor engineering design and and implementation. I am a degreed practicing EE who has been working in the telecommunications field for over thirty years.

          1. I think the main issue was the old switches were not exactly flexible. It had to be an all or nothing switch over. You couldn’t just reroute a banks of lines at a time to the new switch as the old switch wouldn’t be able to route calls to the new one. With ESS onward its pretty easy.

    1. We had one trades assistant who cut a very large *live* and active trunking cable on a dumb exchange. Almost everything goes via a trunking cable on a dumb exchange.

      I was given the job of cutting everything over to a microwave link as that was much quicker than digging holes for cables. We had about a third of the traffic back on day one and probably 99.5 at the end of day 2. The area was about 15,000 customers.

      The *big boss* was going to sack the trades assistant. I said to him that this sort of job should never be given to an assistant or apprentice – sack the person who gave him the job.

      It turned out the the tech that gave him the job was hostile to him and deliberately gave him a task that was beyond his experience. There was quite an *investigation*.

  1. I bet that still left lots of shorted pairs.
    Connecting in the new, can be done by pulling out scores of plastic “Wedges” with lots of (wax covered) twine, that in turn connect the new exchange to the customer lines, previously wired in parallel with the old system. “Step by Step”? Does no one over there remember the name “Strowger”?
    https://en.wikipedia.org/wiki/Almon_Brown_Strowger
    He was one of yours after all!

    1. I do remember Strowger, and he’ll feature prominently in an upcoming feature I’m working on about the evolution of telephone networks. I just used the SxS lingo because that’s what the telcos called Strowger gear in its later incarnations.

      By “one of yours”, I’m guessing you mean that he was a hacker, not that we’re undertakers. For a micro-spoiler of the upcoming article, Strowger was an undertaker who invented automated switching to win back the business that he was losing to the other undertaker in town, whose wife was using her position as the switchboard operator to steer business to her DH. The story may be apocryphal, but it’s plausible and kind of fun.

        1. Far as I know, there’s no downloadable copy of “The Car” episode that partway through it is free of a horrible field order and synchronization problem. The PAL and NTSC DVDs were digitized from the master broadcast tapes and whomever did it did not *watch* the video while doing it. The foulup on that episode went into the digital masters for the DVDs, which apparently nobody watched all of to ensure everything was good.

          What I’d love to see as a crowdfunded project is to buy the master *films* and have them digitized for a new DVD and Blu-Ray release. Tim Hunkin told me via e-mail that it would cost around $16K to buy the films, dunno if that would be for the originals or copies. Then there would be costs of digitizing, putting together the disc menus, disc production etc.

          Until someone does that, the only way there will be a good copy of “The Car” to download is if someone recorded it back in the 90’s and still has it on tape – sort of like the Star Wars Holiday Special, except much better program content. I watched the original US showings of The Secret Life of Machines on Discovery Channel and “The Car” had no glitches in it. (I also saw the one and only broadcast of the SWHS.)

    2. I suspect the Bell system called them step by step because they wanted nothing to do with Strowger’s invention until the basic patents ran out! When I worked for GTE at the lab that was once Strowger’s automatic electric company we called them Strowger switches and even had a display in the lobby with his original patent and a replica of some of the early equipment.

  2. I’ve seen some footage from the UK, where lots of plugs were tied with string to long planks of wood, to be pulled out when changing over from strowger switching

  3. When Pacific Northwest Bell did the decided to convert their entire network to electronic switching in the mid-80s, their director of network engineering pushed to have the old electro-mechanical switches preserved at a newly created museum. Its still around and is now known as The Museum of Communications. It’s in Seattle, north of Boeing Field, housed in a couple floors of a telephone central office. They have a small SxS, part of an old panel switch, and two generations of crossbar switch. All are interconnected and (mostly) operational.

    They also have an ESS they are working on bringing up, and lots of other stuff too!
    http://museumofcommunications.org

    1. Great! Too many times when there is a new paradigm, the old gets discarded, and no one (in authority) thinks to preserve a vital link of the past.
      I remember playing around my grandpa’s “scrap metal heap” and seeing things that now sell in antique stores.

  4. I’ve gotta be missing something. Maybe it’s because I’m so used to today’s technology, but why did they have to cut them so quickly? Why couldn’t they throw a switch, have the lines route to the new system and bypass the old, then have one guy go in and rip out the old?

    1. One two-pole switch for every single pair of cables? No. They wire up everything in parallel, shut down the old system, cut the cables, start up the new. Then go and pull the now-disconnected leg of the parallel feed.

    2. On an office conversion from mechanical to digital, it is an all or nothing deal. Interoffice trunks are thrown to the new office from the upstream office (toll, class4, class 4/5, etc), isolating the old. No calls in to or out from the old office to the outside world at that point. Chopping the cables off takes the old pairs completely (hopefully) out of service, leaving the old office isolated. This type of conversion makes it impossible to go back to the old office of course.
      The analog offices usually had no capability to route part of the switch to the new office, part to the old. New office could do it, but would be a translation nightmare.

    1. It’s been a long time since I’ve been in a CO (central office), while the switching equipment did shrink in size considerably, the terminal / breakout of individual lines still required approximately the same amount of space (per circuit), and I believe copper pairs usage continued to increase until at least 2005-2010. I have seen smaller office locations (not an actual CO) reduce their physical lease space when they were located in non-telecom owned buildings. I doubt telecoms would consider the rent income of the otherwise empty space sufficiently worth the potential risk to physical security of their network to consider letting outsiders into their CO buildings.

    2. My dad worked for AT&T for 15 years then another 15 after the break-up. He told me that the older AT&T buildings were made of thick concrete, usually by military contractors, because communication systems are the first things that need to be restored in case of a disaster. If the buildings are too thick to destroy, then that’s less time spent getting things going again. Remember that a lot of these buildings were constructed during wartime, so it was more about function than form. He also said that key offices had lead in the mix as well as Faraday cages and radiation hardening over most of the systems. In short, the buildings were meant to last, not look good.

      1. Depends on what side of the building you were on, old or new. Clay St. Central Office: Mostly converted over to newer technologies now, at what I can assure you is a more slow, certain, careful pace. The view from the roof is nice :) The battery racks you refer to exist on almost every level with a power plant, I even helped upgrade a few of them: they’re still pretty standard. The newer side of the building is 14 floors and a royal beeyotch to run cable into in places. I’ve done everything in that place, tool & switch, powerplant, grounding upgrades, massive amounts of fiber optic cable runs, the works. I miss the work but not the abuse; since Western Electric/Lucent folded and the Unions were de facto crushed, it’s all subcontractor-of-subcontractor work now that doesn’t pay jack, usually involves ridiculous rules implemented by morons promoted to management via the Peter Principle, and getting stuck undoing the mistakes of even more poorly paid “Engrish as a third language” outsourced contractors. It was fun while it lasted but Telecom is mostly a young kids’ or fools game now.

  5. I’ve had to cut over complete cell sites from one equipment vendor to another, and have had less than 8 hours to prep for and accommodate power, backhaul and RF paths… but that was only a few AC circuits, maybe 6-12 T1’s and maybe 12-18 RF jumpers, and the (literal) support structures, conduits, cable tray and such to go with it.

    So, kudos to these guys getting their CO cut over that quickly without issue!

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