The FCC granted a petition by the California Public Utility Commission to implement two technology-specific, specialized overlay (SOs) area codes for the state of California. The telephone numbers to be assigned in the SOs include those numbers used for services and technologies such as vehicle response systems, E-Fax, automated teller machines, point-of-sales machines, multi-line fax machines, and VoIP services.
One of the SO area codes will cover the northern portion of the state and the other SO area code will cover the southern portion of the state.
Following the FCC decision, the California PUC unanimously approved a plan for an all-services area code overlay to the existing 310 area code in Southern California. The new area code, 424, is expected to help replenish the stock of telephone numbers available within the 310 area code region. Consumers will not have to change numbers for existing services, but may be assigned a different area code for new telephone numbers within the same residence or business where multiple telephone numbers already exist.
Under the new overlay plan, all calls within the 310/424 overlay region must include a "1" followed by the three-digit area code and seven-digit line number. Customers may begin using this dialing pattern beginning December 31, 2005, and must use it starting July 26, 2006. New numbers will begin to be issued using the new 424 area code on or after August 26, 2006.
- The petition was first filed by the California PUC in October 2003.
- The 310 area code was created in late 1991 to relieve number exhaustion in the 213 area code. The 310 area code was subsequently split in January 1997, forming a separate 562 area code, again to replenish number supplies.