Canada was divided into nine numbering plan areas with unique area codes in 1947 when the
American Telephone and Telegraph Company (AT&T) designed the first comprehensive
telephone numbering plan for the North American continent for
Operator Toll Dialing. This was an effort to speed up the connection time of long-distance telephone calls, by eliminating a large group of intermediate telephone operators, and implementing
destination code routing. The effort eventually led to
Direct Distance Dialing (DDD) by telephone subscribers, and the North American Numbering Plan. Yukon, the far northern regions, and Newfoundland and Labrador (which was a
British dominion at the time) were not included in the first assignments of 1947 for lack of telephone service. Locations with service bordering a numbering plan area, were later served with codes of the regional carriers, such as
Northwestel, with toll-routing infrastructure. No numbering plan areas have been split in Canada since 1999. Area codes 807 and 867 are the only remaining Canadian area codes that are not part of an
overlay. Calls within each of these numbering plan areas may be initiated by
seven-digit dialing. == Central office codes ==