408 Area Code – San Jose, California: Location, Time Zone & History

San Jose and Santa Clara County are widely recognized as the historic and cultural core of Silicon Valley, home to the headquarters of major technology companies. Area code 408 has served this ground since March 1, 1959, when it was split from area code 415 in a flash-cut with no permissive dialing period. At its creation, 408 covered a much wider territory, including Santa Clara, Santa Cruz, Monterey, and San Benito Counties.

That territory later narrowed to its present footprint. Effective July 11, 1998, the southern portion of the area, encompassing Santa Cruz, Monterey, and San Benito Counties, split off to form area code 831, with a permissive dialing period that ran through February 20, 1999, leaving 408 to cover Santa Clara County alone. As numbers continued to fill up, the California Public Utilities Commission approved a new overlay code, 669, on October 20, 2011. Mandatory ten-digit local dialing began on October 20, 2012, and the 669 overlay officially went into service the following month, on November 20, 2012.

Today the numbering plan area reaches Sunnyvale, Santa Clara, Cupertino, Milpitas, and Gilroy. Its economy centers on technology and semiconductors, software and internet services, venture capital, advanced manufacturing, and biotechnology, reflecting the region's long-standing identity as the heart of American tech innovation.