I have a thing about the telephone central office (CO). I love spotting them in the wild, giving me some sense of the vast connectedness that they represent, the legal wrangling that took place over their real estate, and their history in our telecommunications connectedness. That is a lot to pack into a series of structures, which is why I am attracted to them.

I wrote that six years ago and it still holds true. This week I added a new CO to my “collection” of favorite places, one that calls itself a connections museum that occupies the top floors of a working CO in an industrial area of Seattle. It is an interesting place, but the label isn’t quite appropriate: it is more an interactive time machine that will take you back over the past 100 years of telecom history. Yes, you will find working models of phones of yesteryear (such as this 1908 wall phone model shown here), but the real treat — especially for this networking geek — are the electromechanical switch fabrics that were once found in every CO on the planet, and now are extinct.

In the pre-TCPIP, analog landline days, every phone had to be connected via a slender pair of copper wires from one’s home (or business) to the CO. That is a lot of wire. Once that pair entered the CO premises, it was connected to these huge machines to make and receive phone calls. That is a lot of wire that is presently unused, such as what can be found in my own home. I think I used my last landline around 2002 or so.

What is both impressive and hard to comprehend in the Seattle CO is how enormous this equipment is, and how small the current digital switches and IP-based networking gear is by comparison. I have seen numerous mainframe computers and they are no small objects. But panel frames and crossbar switches loom large and have a distinctly oily smell, which gives away their mechanical nature. Even with all of its moving parts — and there are thousands of them — these beasts worked flawlessly for decades to place our phone calls.

The other thing that becomes clear walking around the Seattle CO is how extensible phone tech was. The phone network connected gear of many different vintages — there even were examples of those quirky 1960s-era video phones that we now carry around in our pockets and think nothing unusual of making such calls.

The place is an active test bed for the old phone tech, and numerous volunteers have devoted many hours to try to resurrect the tech into some operational semblance. That is quite an achievement, because the surviving documentation is incomplete or incomprehensible or both. Trial by error and patience are important skills to make this stuff come back to life.

Museum docents will take you around the CO, patiently explain what is going on, and show you the process of completing a phone call from one phone to another. There are also phone switchboards that Ernestine would be at home operating, and visitors can do the one-ringy-dingy themlseves.

One thing that I had forgotten about was the importance of real estate with these COs. Back in the 2000s, when DSL technology was coming into vogue, the local phone companies weren’t too happy about having some competition for their communications and tried to stop the DSL vendors from installing their gear in the COs. What became obvious as they attempted to create legal roadblocks was there was plenty of room for the new stuff. This is because as these old crossbar switches were replaced, there was plenty of floor space to hold a couple of 19-inch racks of digital gear. (BTW, that standard harks back to the 1890s.)

As I was leaving the CO, a tour group was coming in. The group was dressed up in what they called steam punk costumes (it looked more Dickensian to my untrained eye) but seemed very appropriate: people who understand the broad sweep of history and wanted to recall a bygone era. While I didn’t need any change of clothes, I recognized kindred spirits.