In the movie Ghostbusters, people plagued by poltergeists were urged to pick up their phones and call 555-2368. In HBO’s The Sopranos, Tony’s cell number was 555-0157. And to call the infamous American Pie band camp, you’d dial 555-0170.

An eerie coincidence? Nope, just a prefix that’s gained celebrity, or maybe cult, status. Virtually every phone number in the movies and on TV starts with 555. Neustar’s John Manning explains why.

Hollywood’s Favorite Prefix

“As part of the North American Numbering Plan, the 555 prefix has numbers set aside for fictitious purposes,” says Manning, senior director of NANPA operations. “Using real numbers in movies, for instance, creates real problems. When someone’s actual number was used in the movie Bruce Almighty, that unlucky soul got calls from people asking for God. The same sort of thing happened when Tommy Tutone sang about 867-5309.”

From time to time, Manning gets calls on behalf of Hollywood producers checking to see if 555 is still the prefix to use. For example, he recently heard from staffers at Saturday Night Live. “Occasionally, someone concerned about making their film more lifelike will want a different prefix,” he says. “I tell them they’re stuck with 555, unless they want to purchase a real number. But I tell them they will need to keep that number for a long, long time, so the next person who gets it doesn’t have to deal with cranks.”

No One on the Line

Originally devoted to weather, time and directory assistance, the 555 prefix was opened up for other informational purposes after the breakup of the Bell System in the 1980s. Anyone can use 555 along with the four-digit numbers 0100 through 0199. If you call one of these numbers, it may or may not ring. But don’t hold your breath for an answer.

“Being a numbering geek, I pay close attention to see if shows are using the right number,” says Manning. “Not long ago, I saw a movie set in the ‘70s that used a number from today. Busted! Okay, not that anyone else would care.”

Want to know more about 555? See a list of 555 numbers used by Hollywood over the years.