Area code 858 is a California telephone area code that was split from area code 619 on June 12, 1999. It is located in San Diego County, California. It covers some northern suburbs of San Diego, California and the northern half of the city proper, including the areas of Del Mar, Poway, La Jolla, Pacific Beach, Clairemont and MCAS Miramar. The outer northern suburbs of San Diego and the mountainous areas to the east (such as Ramona, Santa Ysabel, Warner Springs and Julian) are serviced by area codes 442 and 760, which were a result of an earlier split (and overlay) of area code 619.