Telco history has always intrigued me. I work in a Telco CO and even this building has lot of history in it. The area where my office is now is actually where the old stepper switch used to be. Something like this:
I unfortunately never got to witness any of it in operation as it's before my time, but we do have the odd parts lying around.
Now days most stuff is running on DMS switches, which itself is pretty old. Late 70's vintage. They are working on phasing out some of that stuff to various VOIP based technologies and FTTH, so there is not really an actual central switch where the line connects but rather it's all software based through whatever protocol they use on the fibre. The "switch" is basically at the ONT and that's where the dialtone originates from.
Traditional phone actually has individual pairs all going to a frame which is cross connected to the line equipment, and also DSL if it's setup. Looks like this:
I've worked on it before, it's kinda interesting to think that the copper physically goes all the way to each individual customer. The cables downstairs can have 900+ pairs in them and they go out to the street and split off to neighbourhoods as they go further. That's normally the limiting factor to DSL speeds or even dialup back in the day. Lines with lot of taps or in poor conditions that get wet etc will have bad signal quality. The big cables have air pumped in them to try to keep water out.
You can also troubleshoot phone issues on there as you can connect a test set to the terminals to determine if an issue is on the outside or inside of the CO. My favourite is when I'm trying to terminate a new phone and someone keeps calling it. Nothing like a 170 volt zing to wake you up.
Been a while since I've touched that though, but when I was doing it, it was mostly out orders, but still lot of businesses using hard lines.