Mount Hamilton, CA utilizes an area code overlay in which area codes 408 and 669 serve the same geographic area. The area code overlay was put into service on November 20, 1012 at which time area code 669 was implemented as an overlay of area code 408. Area code 408 was created from a split of area code 415 and put into service on Jaunary 1, 1959. Ten digit dialing (area code + seven digit number) is necessary because two different homes in the same geographic area can have the same seven digit phone number but each would have a different area code.
In addition to Mount Hamilton, CA area codes 408 and 669 serve most of Santa Clara County including the larger cities and communities of Campbell, Gilroy, Los Gatos, Milpitas, Morgan Hill, San Jose, Santa Clara, Saratoga and Sunnyvale in addition to many smaller communities.
Mount Hamilton, CA is located in Santa Clara County and observes the Pacific Time Zone. View our Times by Area Code tool.