In the middle of the film’s initial release, to keep interest going, Ivan Reitman ran a trailer that was basically the commercial the Ghostbusters used in the movie, but the 555 number was replaced with a 1-800 number, allowing people to actually call in. Callers got a recorded message of Bill Murray and Dan Aykroyd saying something to the effect of “Hi. We’re out catching ghosts right now.” They got 1,000 calls per hour, 24 hours a day, for six weeks.
Read more behind-the-scenes facts at IMDb: Ghostbusters (1984) Trivia.
The Devil's Muse 