Beginning Sunday, residents in the 562, 626, 949 and 951 area codes will need to dial the area code first when making phone calls, even if they’re calling someone in the same area code.

The transition to so-called “10-digit dialing” is happening in 82 area codes in 35 states and one U.S. territory, according to the Federal Communications Commission.

Those areas allow phone numbers with “988” as the first three digits. However, 988 is also the number officials are planning to use for the National Suicide Prevention Lifeline beginning on July 16, 2022. The transition to 10-digit dialing is necessary to facilitate easy use of that system, according to the FCC.

The transition will not affect anyone’s current telephone number. Callers in California may be required to dial the number “1” before the area code and seven-digit phone number for local calls.