Video: Telephones got their start in the late nineteenth century, connected through exchanges. In the early twentieth century, however, Bell introduced a new dial system, and needed to tell callers how to use it. The new rotary telephones were a major departure from that of early phones, and would soon become widespread. To get callers prepared, the company sent a film to local theatres, demonstrating its use:
This short subject newsreel was shown in movie theatres the week before a town's or region's telephone exchange was to be converted to dial service. It's extremely short — a little over a minute, like a PSA. The film concisely explains how to use a dial telephone, including how to dial, how to recognise dial tone, and how to recognise a busy signal.
The first dial telephone was manufactured in 1897. It was part of an automatic switching/dialling system invented by Almon Strowger and patented in 1889. (You can see this switching system in action on the film "The Step By Step Switch"). But the Bell System didn't start to roll out Strowger's invention until 1919, though they did showcase the technology in 1904. In 1922, New York City was introduced to dial. The first popularised dial telephone was a desk set candlestick model; the smaller, more familiar desk set came later.
It took decades for dial to sweep the entire Bell System. The last holdout was Catalina Island, off the coast of California, which finally converted to dial in 1978. In Camp Shohola, Pennsylvania, an internal automatic switch system still connects campers with the outside world, it's the oldest functioning Strowger switch in the world.
Eventually, the rotary phone was overtaken with touch-tone phones, beginning in the 1970s. It's interesting to see just how phones have changed, and how people had to become acclimated to their use after their deployment.
This video could be useful today to educate someone who's only ever grown up with a mobile phone.