Area Code Overlay

The telecommunications network is constructed to ensure that calls are routed correctly. Every number plan area (NPA) or area code has a limited amount of telephone numbers. Prior to an area code exhaust of available numbers, the UTC along with the North American Numbering Plan Administrator (NANPA) work alongside industry service providers to implement area code relief to resupply telephone numbers.

A new area code (564) was implemented in Western Washington in 2017 in Docket UT-143787

The (564) area code was created to assign numbers as each of the following western Washington area codes become exhausted: 360, 206, 253, and 425.

As part of a step approach in Western Washington, the 564 area code was first used as a relief to the 360 area code in August of 2017.

Next, on June 15, 2023, The Commission issued Order 1 in Docket UT-230108 initiating the next step in Western Washington covering the 206 area code:

The 564 area code will be used to relieve the 206 area code and implementation of this overlay project has begun. Starting June 10, 2025, customers may be assigned a number in the 564 area code when they request new service or an additional line.  Customers receiving the 564 area code will use the current dialing procedure requiring callers to dial 10 digits when placing a call.

Currently assigned phone numbers, along with subscriber’s terms of service and rates will not be affected by this change.

For any additional questions please email Melissa.castaneda-kerson@utc.wa.gov or call 888-333-9882.  

Resources

• North American Numbering Plan Administrator website.
• Washington State Area Codes and Numbering Issues
• Docket UT-230108
• Docket UT-143787

See map below for more information: