California area code 760 covering cities such as Calipatria, Escondido, Carlsbad, Encinitas and more (all cities here) will have an overlay code starting November 21, 2009. The new area code 442 will cover the same area currently served by 760. The permissive dialing period started on May 2, 2009 and will end on October 24, 2009. During the permissive period local numbers in area code 760 can be dialed using both dialing formats (xxx xxxx and 1 760 xxx xxxx). Starting October 24, 2009 all calls within 760 and 442 area codes should be dialed using the latter. The new area code will become active on Nov. 21, 2009.
See NANPA announcement and map of the new overlay complex 706/442 (PDF).