In 1947, the
American Telephone and Telegraph Company (AT&T) devised the first nationwide
telephone numbering plan and assigned the
original North American area codes. The state of California was divided into three numbering plan areas (NPAs) with distinct area codes:
213,
415, and
916, for the southern, central, and northern parts of the state, respectively. California area codes were reorganized geographically in 1950, so that 916 was assigned to a numbering plan area that comprised only the northeastern part from the
Sierra Nevada to the
Central Valley. The coastal area to the west was assigned
area code 415. Area code 408 was split from numbering plan area 415 on March 1, 1959. The new numbering plan area included most of
Santa Clara,
Santa Cruz,
Monterey and
San Benito Counties. In 1997, the California/Nevada Code Administrator (C/NCA) advised the
North American Numbering Plan Administration (NANPA) of the need for area code relief in the 408 numbering plan area. A geographic
area code split had been approved by the California Public Utilities Commission (CPUC) which would install area code 831 for a new numbering plan area comprising the communities of Santa Cruz, Salinas, Monterey, and Hollister. Area code 408 would be retained in Sunnyvale, San Jose, Los Gatos, and Gilroy. The area code split became effective on July 11, 1998, with a permissive dialing period ending on February 20, 1999. Due to the relatively small size of the area (in both area and population), exhaustion of 831 is unlikely for the foreseeable future. ==Service area==