Turlockers — and everyone else in the 209 area code — will have to use 10-digit numbers, and sometimes a 1 before that, to place calls and texts come Sunday, as part of an area code relief plan.

The 209 area code is expected to be depleted of available prefixes by December 2022. This prompted the Federal Communications Commission to mandate the California Public Utilities Commission adopt an area code relief plan to provide additional numbering resources. A new area code will be introduced on top of the 209 area code using the overlay method, pending approval by the CPUC. The new area code will provide additional prefixes and new telephone numbers for customers requesting new telephone numbers.

All current customers will keep their existing area code and telephone number.

Ten-digit dialing is an FCC requirement for an overlay, so all customers in the two area codes are treated alike. Those using a landline telephone will need to manually dial 1 first before the area code and remaining seven digits, starting Sunday for all local and non-local calls.

Most cell phones automatically add the 1 in front of dialed area codes, but some people may also need to manually enter the 1 first before the remaining 10 digits. Phone numbers saved in contact lists will also need to be updated if they don’t include the area code.

Dialing 1+209 will not change what a call costs and does not mean that a call is a toll or long-distance call, according to the CPUC. Calling areas and rates will not change. What is a local call before the overlay will remain a local call after the overlay. Calls to 911, as well as 211, will not be affected and will continue to be dialed with three digits.

The 209 area code currently includes Amador, Calaveras, San Joaquin, Stanislaus, Tuolumne, Merced, and Mariposa counties, and portions of Alameda, Sacramento, El Dorado, Alpine, Madera and Fresno counties.

Increasing use of phones and phone numbers has created the current shortage of available phone numbers in the 209 area code.

“The new area code will provide additional prefixes and new telephone numbers for customers requesting new telephone numbers,” the CPUC states. “For the 209 area code, an overlay is the only option to ensure the availability of telephone numbers in the geographic area.”

When that new area code will be introduced has yet to be announced.

The reason the 1+10-digit calling being put into place now is because of the 209 is one of the nine California area codes affected by the FCC’s designation of “988” as the 3-digit number for the National Suicide Prevention Lifeline.

Questions and comments about the 209 area code can be submitted to the CPUC Public Advisor by phone: (866) 849-8390; by email: public.advisor@cpuc.ca.gov; and by postal mail: CPUC Public Advisor’s Office, 320 W. 4th Street, Suite 500 Los Angeles, CA 90013.