A new area code was implemented in Western Washington in 2017.
The area code, 564, was created to assign as numbers become exhausted in the 360, 206, 253, and 425 area codes.
Part of this roll out included the implementation of mandatory 10-digit dialing for all western Washington area codes, which required callers to dial all 10 digits of a telephone number, including area code, when making local calls.
Resources
- North American Numbering Plan Administrator website.