california overlay area code
California is currently using thirty two area codes, six of which were created as area code overlays. Area Code 628 is the most recent area code introduced. It was implemented as an overlay of area code 415 on March 21, 2015. California originally had three area codes, 213, 415, and 916 when the numbering system was established in 1947. By 1951, just four years later, California experienced sufficient growth in population and telephone use to need an additional area code.