In the United States (including its territories), Canada, Bermuda, and 16 Caribbean nations, area codes are regulated by the North American Numbering Plan. Currently, all area codes (officially called - numbering plan areas - ) in the NANP must have 3 digits. Historically, the second digit was always "0" or "1", while the second digit of the 3-digit exchange prefix was never "0" or "1." With the increased demand for area codes because of additional lines, FAX lines, pagers, cell phones, etc., the restrictions on the second digit were lifted.