Way back when I started with Bell Labs in 1978, my job was to go around the country and work on various special projects which mostly entailed swapping out old technology for "new" technology (new in parens because what was new then is of course considered ancient now). Many of the examples ended up in this museum which was the Telecommunications Pioneers Museum originally if memory serves me.

A few really fun examples of swap out projects I worked on (usually the first office applications).

1. One really fun one was swapping out what they called MECOBS (I wish I remember what the acronym stood for) but it was an old timey Cord Board system where there were a bunch of operators sitting in front of cord boards (think Lilly Tomlin playing an operator, younger folks can google that). They had a clock printer in front of them and it would punch a Hollerith card with the start time, attach it to a cord plugged and then punch it again at the end. There was a conveyor belt that would carry it to the end of the room where someone would load all the cards into a reader attached to and old IBM computer. Of course, we changed it to a new "electronic digital version". Fun stuff. I grabbed a bunch of the cord and jack combos.

2. There was a system for counting "pegs" on a cross bar switch. A cross bar switch was an old fashioned elecro-mechanical switch, it was noisier than heck. They had a counter, a mechanical counter that attached to a trunk and every time a call was picked up on it, a small lever would click the mechanical counter over. It was a peg counter they called it, it counted up the number of calls. Once a week a woman (always was back then they got the crummy jobs back then) would come out and take a picture of it, there was a little sign above it with the trunk group number above it, they would take the picture with a polaroid camera. Then all those would go to other women who would carefully enter the values in a big pager ledger which then went to engineers who would draw a graph to do the forecast. My job was to replace it. We put in a microprocessor that replaced the mechanical counters and you could dial into it with a modem. I wrote a shell script on a pdp 11/70 running Unix that replaced all that including making the graphs with a plotter. No code required, just all shell crons etc. Unix was a work horse and an amazing advancement at the time.

3. I was called to Seattle as it happens, to swap out a telegraph office to the new X.25 based Digipac system. I went to the office and met the guy who had been maintaining it for the last 50 years or whatever. He had a long grey beard and it looks like the PCB's from all the high voltage coils had mumified him. But he was a nice guy and when I said sort of "hi i am here from HQ to swap out the old High voltage stuff (10 baud !!) to new stuff he said, oh good I can finally retire. That was the most amazing stuff, all of it looked like something that Tesla himself hand wound.

There are a bunch of other fantastic ones like the panel office (a robotic like electromechanical office that had a giant screw etc.) and this new fancy High Capacity Mobile Telephone System HCMTS (later called Cellular) that replaced the old timey MTS (see old timey car phones with a giant box in the trunk). I also worked on a bunch of other cool automated circuit testing systems and eventually worked for a couple of startups that did similar stuff.

Definitely check out the museum, or just that old stuff, it is really interesting the ingenuity those old timers had, so amazing.