Released in 1984, Ghostbusters was the the highest-grossing comedy of all time until Home Alone came along in 1990 and kicked it to the curb.
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.
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