Area code 831, Telephone prefix in Central Coast, California, US.
The 831 area code is a telephone prefix along California's central coast that covers Monterey, Santa Cruz, and San Benito counties. It extends from the Pacific shoreline to the inland farming valleys, connecting coastal towns with rural communities.
The prefix was split from the former 408 code in 1998 to meet growing demand for telephone numbers. The division followed decades of communication network expansion along the California coast.
The numbering plan area includes the agricultural center of Salinas Valley, the technology-driven Santa Cruz region, and the marine research facilities of Monterey Bay.
Local calls within the zone do not require the prefix when both numbers are in the same area. Most mobile carriers offer continuous network coverage along the coast and in populated valleys.
The zone includes both the windswept cliffs of Big Sur and the sun-dried vineyards of Salinas Valley. In some mountain areas, mobile reception remains patchy, highlighting the rural character of these coastal regions.
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