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 implement number conservation measures in accordance with Public Utilities Code Section 7930-7943.
As of September 2018, California has 34 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 ten area codes using the overlay method since 2016.
| Existing Area Code |
Locality
|
Area Code Added |
Effective Date |
Form |
| 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 21, 2018, the CPUC ordered an overlay for the 510 area code in Alameda
and Contra Costa Counties. The new 341
area code will be introduced on July 22, 2019.
The 909 area
code is the next area code to be depleted of available prefixes. The 909 area code is projected to run out of
available prefixes by September 2021.