The dramatic population growth of California can be measured in demographics, development and density … but also in digits. Specifically, telephone area codes, which can hit a ceiling after there are no longer any available prefixes for numbers under them due to high demand.

Take the 707 area code, which covers many counties in Nothern California. These areas were originally in the 415 area code, but 707 was added in 1959 to keep up with demand.

Now 707 is set to run out of prefixes by December 2023, so the California Public Utilities Commission has approved a second area code for the region, called an “overlay,” which will be 369.

The new area code goes into effect in February and will only go out to new service customers or additional lines. People with existing numbers beginning with 707 will not be affected. Local calls will remain local and there will be no changes to the price of calls, coverage areas, or other rates or services, the CPUC said.

The new 369 area code will cover portions of Del Norte, Glenn, Humboldt, Lake, Marin, Mendocino, Napa, Solano, Sonoma, Tehama and Trinity counties and the cities of American Canyon, Arcata, Benicia, Calistoga, Clearlake, Cloverdale, Cotati, Crescent City, Dixon, Eureka, Fairfield, Ferndale, Fort Bragg, Healdsburg, Lakeport, Napa, Novato, Petaluma, Point Arena, Rio Dell, Rio Vista, Rohnert Park, Saint Helena, Santa Rosa, Sebastopol, Sonoma, Suisun City, Trinidad, Ukiah, Vacaville, Vallejo, Windsor, Willits, and Yountville, as well as unincorporated communities.