A 1936 Film Reel by AT&T Prepares Viewers for the Impending Switch to Rotary Dial Telephones
by Glen Tickle from Laughing Squid on (#12A1F)

A 1936 film reel by AT&T prepares viewers for the impending switch to rotary dial telephones by explaining how the machines work, including a visual guide to dialing. The film is part of AT&T's digital archive that includes clips from throughout the company's history.
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.
via reddit