We tend to forget these days that elevators once had operators. Pressing the call button displayed a signal in the car and the operator took the car to the location.
In the 1960 movie "The Apartment", the fancy modern office building had elevator operators, and one operator figured prominently in the plot.
"The Day The Earth Stood Still" was on tonight (early 1950s) and they travelled in an automatic elevator. I thought they didn't come out until the late 1950s.
I remember in some late 1950s buildings the buttons were touch sensitive, you just touched them (no pressing) and they registered.
Many office buildings and department stores maintained operators well into the 1970s.
Automatic elevators require some logic, not only to start and stop the car and position it properly, but also to respond to floor calls and cabin settings. In office buildings, there was logic to move cars to meet peak needs, such as up in the morning and down in the afternoon. That was available by the early 1960s.
The Bell System had a particular model telephone set for elevator use, designed to squeeze into a box. Today the phones are auto dial intercoms. They make me nervous because I wonder if someone will always answer at the other end or a machine will pick up requiring the pressing of tone keys, obviously not possible on a sealed autodialer unit.
BTW, "The Day The Earth Stood Still" is an excellent movie. Shows how paranoid people can get.
It was done in B&W and B&W films had to make good use of lighting. Shadows and texture were very carefully utilized to give film depth and character, that is something sometimes lost in color.
"The Apartment" is an excellent movie, too. Good satire of bullpen office life. The office machines may be different, but the atmosphere hasn't changed much. Good scene of someone using a keyset, the line buttons lamps worked exactly in relation to the hookswitch, even flickering a bit when the phone was gently hung up; that's rare.