Area Code Atlas

NANP- Overlay of 360 Numbering Plan Area (NPA) with 564 NPA (Washington)

NPA 564 planned as overlay for 360

Area code 564 was first proposed in 1999 to relieve number shortages in area code 360, with an initial planned in-service date of August 1, 2000.

NPA 564 to Overlay NPAs 206, 253, 360, and 425 (Washington)

NPA 564 overlay plan expanded to include 206, 253, and 425

The overlay plan for area code 564 was expanded in 2000 to include the metropolitan Seattle area codes 206, 253, and 425, anticipating exhaustion in those NPAs.

Suspension of 564 Overlay (Washington)

Implementation of 564 overlay suspended

The implementation of the 564 overlay was suspended in 2001 due to increased efficiency in number pooling and a downturn in telecommunications demand, delaying the need for the new area code.

Overlay planned for NPA 360 with new code 564

The Washington Utilities and Transportation Commission approved the overlay of area code 360 with a new area code 564 in May 2016 to provide numbering relief for western Washington.

Order adopting implementation plan for 564 overlay

The Washington Utilities and Transportation Commission adopted an implementation plan in 2016 to activate area code 564 as an overlay for area code 360.

NPA 564 overlay on 360 announced

NPA 564 to Overlay NPA 360 (Washington)

Overlay of area code 564 in Washington

In 2017, area code 564 was introduced as an overlay for the 360 area code region in Western Washington due to number exhaustion, allowing new numbers to be assigned with 564 in the same geographic area.

Area code 564 planned as overlay for 206, 253, and 425

Since 2017, area code 564 has been planned to overlay area codes 206, 253, and 425 in Washington state to provide relief when central office code exhaustion demands it.

Ten-digit dialing mandatory in western Washington

Ten-digit dialing became mandatory for all of western Washington in 2017, coinciding with the introduction of the 564 overlay.

Permissive 10-digit dialing begins for 206, 253, 360, 425, and 564 (specific to 360 and overlay)

Permissive 10-digit dialing began on January 28, 2017, for area codes 206, 253, 360, 425, and the new overlay 564, allowing both 7-digit and 10-digit dialing during the transition. This includes specific permissive dialing for the 360 area code and the 564 overlay region.

Mandatory ten-digit dialing begins in western Washington

Mandatory ten-digit dialing began on July 29, 2017, for all calls in western Washington, including area codes 206, 253, 360, 425, and the new overlay 564.

NPA 564 overlay activated on NPA 360

Area code 564 was activated as an overlay on area code 360 on August 28, 2017, requiring ten-digit dialing for all calls in western Washington.

NPA 564 planned to overlay 253, 206, and 425

Area code 564, first activated as an overlay for 360 in 2017, is planned to overlay additional area codes in western Washington, including 253, 206, and 425, when number exhaustion requires relief.

Area code 564 numbers issued in 360 region

Telephone numbers with area code 564 began to be issued in the existing 360 numbering plan area starting September 30, 2017.

Expansion of 564 overlay approved to include 206 in Seattle area

On June 15, 2023, the Washington Utilities and Transportation Commission approved the expansion of area code 564 to overlay the 206 numbering plan area, extending the overlay to metropolitan Seattle to address projected number exhaustion in 2025.

NPA 564 overlay on 206 announced

NPA 564 to Overlay NPA 206 (Washington)

NPA 564 overlays 206

On June 10, 2025, the 564 area code was expanded to overlay the 206 numbering plan area in the Seattle region. This expansion allowed new numbers to be assigned with 564 following the exhaustion of available 206 central office codes. Providers began activating central office codes for 564 in the 206 area once all 206 codes had been allocated.