555 (telephone number)

Telephone numbers with the prefix 555 are widely used for fictitious telephone numbers in North American television shows, films, video games, and other media in order to prevent practical jokers and curious callers from bothering real people and organisations by telephoning actual numbers.

Not all numbers that begin with 555 are fictional—for example, 555-1212 is one of the standard numbers for directory assistance throughout the United States and Canada. In fact, only 555-0100 through 555-0199 are now specifically reserved for fictional use; the other numbers have been reserved for actual assignment. The entire 555 exchange is reserved in all overlay North American toll-free area codes (800, 844, 855, 866, 877, 888) and in Canada's rarely used non-geographic area code 600.

Area code 555 in the North American Numbering Plan is reserved for Directory Assistance applications.

Telephone companies began encouraging the producers of television shows and movies to use the 555 prefix for fictional telephone numbers by the 1960s. Two early examples include The Second Time Around (1961), which used 555-3485, and Panic in Year Zero! (1962), which used 555-2106. In television shows made or set in the mid-1960s or earlier, "KLondike 5" or "KLamath 5" reflects the old convention for telephone exchange names. Before "555" or "KLondike-5" gained broad usage, scriptwriters would sometimes invent fake exchanges starting with words like "QUincy" or "ZEbra", as the letters "Q" and "Z" were not used on the old dial phones. Numbers in format "Zenith" X-XXXX, while not directly dialable, were not fictional. These were an early form of regional tollfree number which required operator assistance.

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