• Area Codes and Numbering

  • The North American Numbering Plan (NANP) is the telephone numbering system for the Public Switched Telephone Network in the United States, Canada, and some Caribbean countries. NANPA numbering resources are administered by the North American Numbering Plan Administrator (NANPA). The NANP is divided into smaller Numbering Plan Areas that are each identified by a three-digit code, commonly known as an area code. Telephone numbers in the NANP are structured in the format NPA-NXX-XXXX, in which

    NPA is the 3-digit area code that identifies a specific geographic area;

    NXX is the 3-digit prefix that identifies a specific central office within an area code; and

    XXXX is the 4-digit line number that identifies a specific line within a central office.

    The Federal Communications Commission (FCC) has exclusive jurisdiction over telephone numbering in the United States but has delegated specific authority to state regulatory agencies. Tasked with the authority granted by the FCC, the CPUC conducts area code relief and enforces number conservation in California in accordance with Public Utilities Code Section 7930-7943.

    As of August 2019, California has 35 area codes. A new area code is added to a geographic area when there are no more three-digit prefixes available in the existing area code.

    In recent years, growing consumer demand for advanced technologies and smart devices has led to increasing consumption of telephone numbers. As a result, telephone prefix shortage has occurred in many locations, resulting in the need to add new area codes.

    Area codes are added in the form of a geographic split or an overlay. California has added eleven area codes using the overlay method since 2006.


    Existing Area Code 


    Area Code Added  Effective Date Form
    510 Alameda and portions of Contra Costa Counties 341 7/22/2019 Overlay
    805 Ventura, Santa Barbara and San Luis Obispo Counties 820 6/30/2018 Overlay
    619 San Diego County 858 6/19/2018 Overlay  
    916 Sacramento County 279 3/10/2018 Overlay  
    323 Large portion of City of Los Angeles and surrounding cities 213 8/01/2017 Overlay  
    415 San Francisco County, most of Marin County and small portion of San Mateo County 628 3/21/2015 Overlay  
    408 Most of Santa Clara County and small portions of Alameda and Santa Cruz Counties 669 11/20/2012 Overlay  
    760 Far southeastern third of California 442 11/21/2009 Overlay 
    818 San Fernando Valley area of Los Angeles County 747 5/18/2009 Overlay
    714 Orange County 657 9/21/2008 Overlay  
    310 Westside and South Bay regions of Los Angeles County 424 8/26/2006  Overlay  


    On June 13, 2019, the CPUC ordered an overlay that will add the 840 area code to the existing 909 area code, which serves the southwestern portion of San Bernardino County, the eastern portion of Los Angeles County, and small portions of Orange and Riverside Counties.



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