What is an area code overlay?

An area code overlay is the addition of another area code (341) to the same geographic region served by an existing area code (510). An overlay does not require customers to change their existing area code but does require customers to use a new dialing procedure to complete telephone calls. When an overlay is implemented, customers must dial “1” followed by the area code and the seven-digit telephone number to complete every call, including calls within the same area code.

Who will be affected?

Customers who have a 510 area code telephone number will be affected. Geographic areas that are served by the 510 area code will also be affected. The 510 area code serves 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. The new 341 area code will serve the same geographic area currently served by the existing 510 area code.

What will be the new dialing procedure?

To complete calls from a landline phone, the new dialing procedure requires anyone with a 510 or 341 area code to dial 1 + area code + telephone number. This means that all calls in the 510 area code that are currently dialed with 7 digits will need to be dialed with 11 digits using the new 1 + area code + telephone number dialing procedure.

To complete calls from a cellular or mobile phone, callers may dial area code + telephone number or 1 + area code + telephone number whenever placing a call from a phone number with the 510 or 341 area code.

When will the change begin?

Beginning June 22, 2019, you must use the new dialing procedure, as described above for all calls, even for local calls. On and after this date, if you do not use the new dialing procedure, your calls will not be completed, and a recording will instruct you to hang up and dial again using the new dialing procedure.



Beginning July 22, 2019, the new 341 area code becomes effective, and new telephone lines or services in the area may be given numbers from either the 510 or the 341 area code.

What will you need to do?

In addition to changing your dialing procedure, all services, automatic dialing equipment, or other types of equipment that are programmed to dial 7 digits will need to be reprogrammed to use the new dialing procedure. Some examples are life safety systems and medical monitoring devices, PBXs, fax machines, Internet dial-up numbers, alarm and security systems or gates, speed dialers, call forwarding settings, voicemail services, and other similar services or equipment. You may also want to check your personal and business stationery, checks, advertising materials, websites, contact information, and personal or pet ID tags to ensure the area code is included in the telephone number.

What will remain the same?

Your telephone number, including current area code, will not change.

The price of a call, coverage area, or other rates and services will not change due to the overlay.

What is a local call now will remain a local call regardless of the number of digits dialed.

You can still dial just three digits to reach 911, as well as 211, 311, 411, 511, 611, 711 and 811.

Who may you contact with questions?

If you have any questions regarding information provided in this notice, please call (service provider’s name and number) or access the following websites for more information: (service provider’s website) or www.cpuc.ca.gov/510areacode/.