Twenty-five years ago I read a really wonderful article about how phone numbers actually worked in the dial phone era; it's complicated. I wrote about it in TreeHugger here: From rotary to Siri: How the phone numbering system came and went.:
The switch worked in a linear fashion, so you couldn't have one person with a number 76 and another 7644; it needed all four digits to work. It couldn't start with 0, because that would connect you with the operator before you were finished. They didn't start with 1 either; it was used for internal switching. Needless to say, they soon ran out of numbers and went to seven digit dialing. There was a lot of concern that people couldn't keep track of so many digits, so they gave names to the exchanges, hence Elizabeth Taylor's famous BUtterfield 8 and my grandmother's EMpire 3.
It was also complicated getting people who were used to just picking up a phone and talking to an operator to actually start using the dial phones. Until this video popped up on Gizmodo, from the AT&T archives, I had no idea that they did the switchover in a very short time. According to a quote in Gizmodo:
This short subject newsreel was shown in movie theaters 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 recognize dial tone, and how to recognize a busy signal.
The surprising thing to me is that the sounds have not changed at all, even though they were then made with pretty primitive oscillators and buzzers. It's fascinating to watch how the technology has evolved. The tones may be the same but other things have changed; first ten digit dialling, and then forgetting about numbers altogether as most people have now.