Located in the Pacific (GMT -08:00) time zone. Area code 628 serves the state of California. This area code was assigned on December 19th, 2013. On March 21st, 2015 it went into service. 628 is a General Purpose Code. 628 service area does overlap with 415 area codes. Dialing pattern for local calls within the same NPA (area code) is 1+10D.