First three digits of a nine-digit telephone
number in North
American Numbering Plan
, which designates a 'toll' center (geographical area that allows long-distance calling) in the US and Canada, or a specific country
in the Caribbean. The first digit of an area code
must be between 2 through 9, while any number could be used for second and third digit. The three digits following an area code are called the central office code
code, and the next four digits are called the directory
code, or subscriber number.