Changes coming to the 510 area code

Owner of a phone with a 510 area code? Time to start dialing 10 digits when making a call to someone else in the 510.

So says the California Public Utilities Commission, which is encouraging 510 carriers to dial 10 numbers instead of seven, beginning today. The volunteer period comes as the CPUC prepares to unveil in 2019 the 341 area code in some areas that carry the 510.

Next month, customers will be required to dial 510 with any call within that area code.

“What it means is that people with a 510 area code can start dialing with the area code included, beginning Saturday,” CPUC spokesman Christopher Chow said Friday. “It won’t be until July of next year that carriers will be able to assign numbers a 341.”

The 510 area code serves the western portions of Alameda and Contra Costa counties, and the change stems from the projection that the 510 will run out of prefixes — the three numbers that follow the area code — before the summer of 2019.

Customers who use 510 are encouraged to reprogram the auto and speed dials on their phones, as well as the modems on their computers, to include the area code.

The 510 area code entered the picture in September 1991 when it split off from the 415, currently used in San Francisco and Marin County; it serves Alameda, Albany, Berkeley, Emeryville, Fremont, Hayward, Newark, Oakland, Piedmont, San Leandro and Union City in Alameda County, as well as El Cerrito, Hercules, Pinole, Richmond and San Pablo in Contra Costa County.

The 925 emerged from the 510 in 1998.