If you watch old movies, you can see the pre-dial telephones in operation as the operators set up calls. It would take a while. One convenience is that you could have the operators call you back when they had reached the other party.
Some years ago, I was shown how to operate a (enclosed) freight elevator by someone who apparently thought I was kind of dumb not to know how they worked. I don't know how common the setup was, nor how old or typical it was, but among the features it lacked that modern passenger elevators have - it didn't travel to and stop at a floor automatically; you had to start and stop it with a control at the right spot; it didn't open and close the doors automatically; you had to pull on a strap, and close guards separately, and I'm not sure I even recall any locking mechanism.
I seem to recall that there was a locking system but I can't quite recall what it was. It was either that here was some sort of piece of metal that stuck out from the lift shaft and only allowed the doors to be opened at certain positions in the shaft, or that the lift wouldn't operate without the doors being closed, or some combination of both.
They, unfortunately, are on a higher floor with no elevator. So every time they have to talk on the phone they have to get 3+ flights of stairs.