In the North American Numbering Plan, telephone numbers all consist of a 3 digit area code, a 3 digit office code (or exchange), and a 4 digit station number. When written the 3 components are typically separated by dashes, or in some cases periods – for example 206-965-9805.
To prevent real telephone numbers from appearing where they perhaps shouldn’t, phone numbers in the range 555-0100 through 0199 are reserved for “fictional” numbers. (Most assume that the entire 555 office code is so reserved, but apparently not.) What this means is that in books, movies or television when a phone number is presented it’s typically a 555 number.
Knowing this, the use of a 555 number immediately breaks suspension of disbelief for many. “Oh, yeah. We’re watching a movie.”
