• 510 Area Code

    On June 21, 2018, the CPUC acted to ensure that phone numbers continue to be available to meet the demand in the geographic region served by the 510 area code by approving a second area code (called an overlay) that will provide additional numbering resources while minimizing customer inconvenience. The new area code that will be added to the 510 region is 341. Read our press release.

    Background Information

    On May 19, 2017, the North American Numbering Plan Administrator (NANPA) filed Application 17-05-013 with the California Public Utilities Commission (CPUC) to introduce a new area code to the area now served by the 510 area code.

    The 510 area code is forecasted to use up all its available prefixes by the 2nd quarter of 2019. Adding a new area code to the 510 area code region will provide additional prefixes and new telephone numbers for customers. The telecommunications service providers have proposed to add the new area code using an overlay.Public Meetings were held on January 17 and February 15, 2017 in Oakland, Berkeley and Hayward. At these meetings, two options to introduce the new area code were presented.

    1. All services overlay:

    An overlay will introduce a new area code to the geographic area currently served by the 510 area code. All current 510 customers will keep their area code and 7-digit telephone number. New telephone customers or those adding additional lines may be assigned numbers from the new area code. 1+10-digit dialing will be required throughout the overlay area as mandated by the Federal Communications Commission. This means all calls, including local calls, within and between the 510 area code and the new area code will have to be dialed using the 1 + area code + 7-digit telephone number procedure.

    2. Geographic split:

    A split would split the 510 region into two areas along the southern boundary of the Oakland: Main-Piedmont DA rate center between the Oakland: Alameda DA and the Oakland: Fruitvale DA rate centers. One side of the split line would be assigned a new area code and the other side would keep the existing 510 area code. Customers on both sides of the split line retain their existing 7-digit telephone numbers and local calls within the same area code continue to be completed by dialing the 7-digit telephone number. However, customers would need to dial 1 + area code + 7-digit telephone number for calls across the split line between the 510 and the new area code. This disparity in dialing could create widespread customer confusion.

    Furthermore, a split for 510 is not feasible as splitting the 510 would fail to comply with the Public Utilities Code Sections with regard to considering city and county boundaries during relief plan evaluation. A split for the 510 would split Oakland and Piedmont, dividing city offices and phone systems into two area codes, resulting in costly and disruptive impacts to Oakland and Piedmont, and possibly affecting response time to 911 emergency calls.

    Attendees at the three 510 public meetings included the general public, local jurisdiction officials, reporters and telecommunications representatives. Attendees were encouraged to ask questions and express their opinions during the Question-and-Answer period. They were further provided an opportunity to submit written comments to the CPUC.

    Public comments were also provided via email and postal mail sent to the Public Advisor’s Office. Concerns and questions expressed in the comments regard issues ranging from whether customers will lose their existing telephone number and the 510 area code to the new 1 + 10-digit dialing procedure and reprogramming of telecommunications services and equipment.

     510 Public Meeting Materials

     510 Public Meeting Staff Report


    The area served by the 510 area code includes the western portions of Alameda and Contra Costa Counties. The 510 area code serves the cities of Alameda, Albany, Berkeley, Emeryville, Fremont, Hayward, Newark, Oakland, Piedmont, San Leandro and Union City in Alameda County; and the cities of El Cerrito, Hercules, Pinole, Richmond, and San Pablo in Contra Costa County.

    510 Area Code Background


    The CPUC appreciates public feedback concerning area code relief for the 510 area code. You may submit comments by:

    • Email to public.advisor@cpuc.ca.gov, or

    • Postal mail to CPUC Public Advisor’s Office, 320 W. 4th Street, Suite 500, Los Angeles, CA 90013.

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