The California Public Utilities Commission, or CPUC, approved 341 as another area code for parts of Alameda and Contra Costa counties’ phone numbers on Thursday, as the 510 area code comes close to exhausting its possible prefixes.

According to a press release from the CPUC, the 510 area code is expected to run out of prefixes, or the first three numbers after the area code, by “the second quarter of 2019.” Adding an “overlay” area code, or a second area code for the same geographic region, will alleviate customer inconveniences by increasing the possible phone number combinations.

The North American Numbering Plan Administrator put in the request in order to meet the demand for more telephone numbers, according to the press release.

The 510 area code was created in 1991 as an offshoot of the 415 code, and the 925 code was created in 1998 as an offshoot of the 510 code. The proposal documents say that the 510 area code serves the following cities: Alameda, Albany, Berkeley, El Cerrito, Emeryville, Fremont, Hayward, Hercules, Newark, Oakland, Piedmont, Pinole, Richmond, San Leandro, San Pablo and Union City, in both Alameda and Contra Costa counties.

While a split — dividing the geographical area to make distinct locations have 341 or 510 as their respective codes — was also considered in the proposal, an overlay was recommended because it would not cause current customers to change their phone numbers.

“An overlay is less confusing and less costly for existing customers because all customers retain the same area code and telephone number,” reads the proposal, which was submitted May 21. “An overlay would not require existing residential or business customers to incur the time and expense to inform family, friends, customers, and business associates of a new area code, or incur the cost of reprinting stationery and other materials.”