The Screaming Telephone was a 1992 Samaritans cinema public information film that featured a terrifying screaming telephone. The PIF starts with a series of abstract animations and audio of a telephone ringing, a wife asking her husband for a divorce, talk of financial problems, and more unpleasant chatter. Suddenly, an animated telephone opens its human-like mouth and lets out a blood-curdling scream of distress. The text "we understand" appears on the screen. If I'd seen this in theaters, I would have thought I was watching a trailer for a horror film.
The Samaritans' public information film below, from 1989, is similarly powerful:
