Area codes 510 and 341
Area codes 510 and 341 are telephone area codes in the North American Numbering Plan (NANP) serving much of the East Bay in the U.S. state of California. The numbering plan area (NPA) includes parts of Contra Costa County and western Alameda County, including the city of Oakland, but excludes Dublin, Livermore, Pleasanton, and Sunol.
Area code 510 was established on September 2, 1991, in an area code split of the 415 numbering plan area.[1] On March 14, 1998, the inland portion of the East Bay was split off as area code 925. The dividing line followed the Berkeley Hills; almost everything west of the hills stayed in 510, while everything east of the hills transferred to 925.
In response to projections that 510 would exhaust its central office prefixes in the second quarter of 2019, the California Public Utilities Commission approved a converaion to an overlay complex with new area code 341. The first central office codes in 341 became available on July 22, 2019.[2][3] Ten-digit dialing became mandatory in the East Bay a month earlier, on June 22.[4]
History
[edit]Introduction of 341
[edit]By 2016, the California Public Utilities Commission (CPUC) projected that NPA 510 would exhaust its numbering pool by the second quarter of 2019. In response, the commission held meetings in Berkeley, Oakland and Hayward in January and February 2017 to discuss area code relief for 510.[2] The North American Numbering Plan Administrator (NANPA) proposed in May 2017 that the CPUC to overlay the numbering plan area with area code 341. NANPA had previously assigned 341 as the relief area code in 1999, but nationwide number pooling procedures eliminated the need at that time. The NANPA retained 341 for the then-future relief of 510.[5] CPUC accepted the NANPA proposal in a decision on June 21, 2018.[3] With the start of the overlay plan in July 2019, all customers in the numbering plan area can be assigned telephone numbers with either code, and must dial the area code for all calls.[6][7]
Prior usage of 510 for TWX
[edit]In 1962, AT&T assigned NPA 510 for conversion to dial service of the Teletypewriter Exchange Service (TWX) in the United States.[8][9] Telex use of area code 510 was decommissioned in 1981 after conversion of the service to new transmission technologies by Western Union,
Service area
[edit]The service area contains the following cities in two counties.
Alameda County
[edit]Contra Costa County
[edit]See also
[edit]References
[edit]- ^ "Archived copy" (PDF). Archived from the original (PDF) on 2011-06-04. Retrieved 2008-09-01.
{{cite web}}: CS1 maint: archived copy as title (link) - ^ a b Prosper, Terrie (2018-06-21). "CPUC Provides More Numbers in 510 Area Code Region" (PDF) (Press release). California Public Utilities Commission. Retrieved 2018-06-21.
- ^ a b California Public Utilities Commission (2018-06-21). "Decision Granting Request for an All-Service Area Code Overlay in the 510 Numbering Plan Area" (PDF). Retrieved 2018-06-21.
- ^ "341 Area Code, New Dialing Procedure Coming To Alameda, Contra Costa Counties". KPIX-TV. 2019-06-21.
- ^ North American Numbering Plan Administrator (2017-05-19). "Application of the North American Numbering Plan Administrator, On Behalf of the California Telecommunications Industry, For Relief of the 510 Numbering Plan Area" (PDF). Retrieved 2018-06-21.
- ^ Avalos, George (2018-06-21). "341 is the East Bay's new telephone area code, joining 510, 925". The Mercury News. Retrieved 2018-06-21.
- ^ "Planning Letter 518: NPA 510 and 341 All-Services Overlay (California)" (PDF). 2018-07-30. Retrieved 2025-07-01.
- ^ Tyberghein, E.J. (July 1962). "TWX Goes Dial". Bell Laboratories Record: 232.
- ^ Traffic Routing Guide, sec. 15-16, AT&T, 1975
External links
[edit]| North: 369/707 | ||
| West: 415/628, 650 | 341/510 | East: 925 |
| South: 408/669 |