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Area code 564
Area code 564
Area code 564
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47°36′35″N 122°19′59″W / 47.60972°N 122.33306°W / 47.60972; -122.33306

Numbering plan areas of Washington and overlay complex 564 (red)

Area code 564 is a telephone overlay area code in the North American Numbering Plan (NANP) for Western Washington state, including metropolitan Seattle. It overlays the combined numbering plan areas of area codes 206 and 360.

The area code was first proposed in 1999 to relieve telephone number shortages of area code 360, but implementation was delayed until 2017, when it was installed as an overlay to numbering plan area (NPA) 360. Neighboring NPAs 206, 253, and 425 were slated for expansion of the overlay complex upon exhaustion of central office codes in each NPA. In 2023, area code 206 was approved for expansion with a guide line for preparation of inclusion of at least nine months.[1] Ten-digit dialing has been mandatory in all of western Washington since July 29, 2017.

History

[edit]

From 1947 to 1957, all of Washington state was assigned area code 206 for routing long-distance telephone calls in Operator Toll Dialing. In 1957, the numbering plan area was split, with area code 509 implemented for the state east of the Cascade Range. This configuration remained in place until 1995, when resource pressure from the proliferation of cell phones, fax machines, and pagers required additional central office prefixes and telephone numbers. Most of the region outside the Seattle and Tacoma areas was split from 206 to form a new numbering plan area with area code 360.

By the late 1990s, projections indicated possible exhaustion once again, so that in 1999, area code 564 was assigned for installation as an overlay of NPA 360, with an in-service date of August 1, 2000.[2]

In May 2000, the Washington Utilities and Transportation Commission (WUTC) projected that the metropolitan Seattle area codes (206, 253, and 425) would also soon exhaust their number pools, and it expanded the 564 plan to include those areas in the overlay.[3] By the summer, however, the relief action was determined not to be immediately necessary. On August 22, 2001, the WUTC announced that increased efficiency in the reuse of the existing number pool meant that the immediate need for the new area code had subsided. Part of that was also attributed to a downturn in the telecommunications sector. The overlay implementation was suspended until at least October 1, 2002.[4]

Since the development of the initial plan for the area code, the WUTC and the NANPA have rejected the telephone companies' request for a new area code and instead directed them to actively share and efficiently use the number blocks that had already been assigned. That refers mainly to the practice of number pooling, which allocates a single telephone exchange prefix in ten blocks of one thousand telephone numbers for more efficient allocation, rather than assigning a prefix's whole numbering space (10,000 numbers) to one carrier in a single rate center.

The WUTC took further steps to decrease the need for new number blocks in 360 and 509 and head off the need for new area codes, including aggressive reclamation of unused and underused number blocks and exchanges. The introduction of mandatory local and wireless number portability (a prerequisite for number pooling) has also served to stem the demand for new numbers and thus new area codes.[5]

According to the WUTC's estimate as of March 2014, the earliest projection for any Western Washington area code to be exhausted was 2018 for area code 360. The other codes were not expected to exhaust before 2025.[5]

Area code 564 was finally implemented on August 28, 2017.[6] Ten-digit dialing had been mandatory since July 29, 2017, for all local calls in Western Washington.[7]

Since September 30, 2017, telephone numbers with the area code 564 have been issued in the existing number plan area 360.[8]

On June 15, 2023, the WUTC approved expanding the coverage of area code 564 to include numbering plan area 206.[1]

Per NANPA analysis and determination, the overlay complex may be extended only as needed when NPAs 206 (which occurred in 2025), 253, or 425 are nearing exhaustion.[9] NPAs 253 and 425 are nowhere near exhaustion.[5]

See also

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References

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Area code 564

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from Grokipedia
Area code 564 is a area code in the (NANP) that serves state in the United States, functioning as an overlay for the existing area codes 360 and 206, with planned overlays for 253 and 425 as needed to address the exhaustion of available telephone numbers in these regions. It covers a broad geographic area including major cities such as , , Bellingham, Olympia, Bremerton, and Longview, primarily in the . Introduced in August 2017, initially as an overlay for , the code was established under Docket UT-143787 by the Washington Utilities and Transportation Commission (UTC) to provide additional numbering resources amid growing demand from and expansion. On June 15, 2023, the UTC approved further expansion via Order 1 in Docket UT-230108, extending 564 to overlay the 206 region effective June 10, 2025, with similar relief planned for 253 and 425 as needed; this change requires 10-digit dialing (area code plus seven-digit number) for all local calls within the affected areas but does not impact existing phone numbers, service plans, or rates. The implementation supports continued access to telephone services for over 4 million residents and businesses in this densely populated corridor along the and extending to the southwestern border with .

Geography

Coverage Area

Area code 564 serves the western portion of Washington state, encompassing coastal and inland regions west of the Cascade Mountains while excluding eastern inland areas. Its boundaries extend from the Canadian border in the north to the Oregon border in the south, and from the Pacific Ocean coastline eastward to approximately the Cascade Range. The area code covers 18 counties, including , Clallam, Cowlitz, , , Jefferson, King, Kitsap, Lewis, Mason, Pacific, Pierce, San Juan, Skagit, Snohomish, Thurston, Wahkiakum, and Whatcom. It serves over 200 cities and communities, such as , Longview, Everett, Marysville, Olympia, Bellingham, Shoreline, and . These areas represent a mix of urban centers, suburban communities, and rural locales in the and along the coast. All locations under area code 564 operate in the Pacific Time Zone, which observes UTC−8 during standard time and UTC−7 during daylight saving time. The code functions as an overlay for area codes 360 and 206, sharing the same geographic footprint without requiring changes to existing phone numbers.

Overlaid Codes

Area code 564 functions as a non-geographic overlay within the North American Numbering Plan (NANP), serving the identical geographic regions as area codes 360 and 206 in western Washington while enabling the allocation of additional telephone numbers without modifying established boundaries. This overlay mechanism provides additional numbering resources in the same geographic area as the overlaid codes, addressing telephone number exhaustion in high-demand areas by introducing a new central office code prefix without requiring geographic splits. The overlay with was initially implemented in 2017, covering non-Seattle portions of to relieve pressure on the existing 360 numbering plan area (NPA). On June 10, 2025, the 564 NPA expanded to overlay , incorporating the metropolitan core and ensuring continued availability of phone numbers in this densely populated region. In overlaid regions, all local calls now necessitate (area code plus seven-digit number) to distinguish between the multiple area codes sharing the same territory, though existing customers are not required to change their numbers. This approach preserves service continuity while accommodating growth in demand, such as from mobile devices and VoIP services.

History

Introduction as 360 Overlay

Area code 564 was introduced as an overlay for the existing 360 area code to address the impending exhaustion of telephone numbers in , driven by significant population growth in the region. The Administrator (NANPA) projected that the 360 area code would run out of available numbers by early 2018, necessitating relief measures to ensure continued telephone service availability without geographic splits. The regulatory process for the 564 overlay began with planning coordinated by and culminated in approval by the Washington Utilities and Transportation Commission (WUTC) in Docket UT-143787 during 2016. This approval aligned with federal guidelines from the and 's numbering resource management protocols, prioritizing an overlay solution to conserve numbering resources across the . Implementation of the 564 area code occurred on August 28, 2017, as an all-services overlay covering the entire 360 service area, which spans much of outside the Puget Sound urban core. Unlike a split, which would require changing numbers for some customers, the overlay added capacity by assigning new 564 numbers to additional lines while leaving existing 360 numbers unchanged, thereby minimizing disruption to established services. Mandatory for local calls within the overlay area began on July 29, 2017, to accommodate the dual area codes. Early adoption of the 564 area code focused on new telephone assignments starting in late 2017, with providers issuing it for fresh activations, mobile services, and additional lines in the 360 region. This phased rollout ensured a smooth transition, as customers with existing 360 numbers retained them indefinitely, while the overlay provided immediate relief to meet growing demand from population increases and new technologies like VoIP.

Expansion to 206 Overlay

The 206 area code, serving the core including the city of and surrounding communities in King County, faced projected exhaustion of its telephone numbers by the end of 2025, driven by sustained population growth, business expansion, and increasing demand for mobile and landline services in the region. This shortage was forecasted by the Administrator () based on usage trends, prompting the need for relief measures to maintain service availability without disrupting existing customers. In response, the Washington Utilities and Transportation Commission (WUTC) approved the expansion of area code 564 to overlay the 206 numbering plan area on June 15, 2023, following a review of NANPA's exhaustion projections and public input. The regulatory process included a nine-month preparation period mandated by the WUTC to coordinate with telecommunications carriers, update switching systems, and ensure compliance with North American Numbering Council guidelines. Implementation began on June 10, 2025, and as of November 2025, new telephone numbers in the 206 geographic region are being assigned the 564 area code as 206 numbers deplete. This approach builds on the 564 code's prior introduction in 2017 as an overlay for the adjacent 360 area code. Mandatory for local calls within the 206/564 region has been enforced since July 29, 2017, to prepare for such expansions. Telecommunications providers such as and Verizon, in collaboration with the WUTC, initiated extensive public notification campaigns starting in early 2025 to educate residents and businesses on the changes. These efforts included informational websites, direct mailings to affected households, bill inserts, and public service announcements across media outlets, emphasizing that existing phone numbers would not change and highlighting the continued requirement for to avoid service disruptions. The overlay expansion provides capacity for approximately 7.7 million additional telephone numbers in the Seattle metro area, effectively doubling the available resources and supporting long-term growth without the need for geographic splits or customer relocations. This measure ensures reliable numbering for the region's estimated 4 million residents and burgeoning tech and service sectors through at least the . As of November 2025, expansions of the 564 overlay to the 253 and 425 areas remain planned as needed based on projections.

References

  1. https://www.utc.wa.gov/regulated-industries/utilities/telecommunications/washington-state-area-codes-and-numbering-issues/564-area-code-overlay
  2. https://www.allareacodes.com/564
  3. https://assets.vonage.com/sfdc/vbs/206-564%2BNPA%2BOverlay%2BCustomer%2BNotice%2BFINAL.pdf
  4. https://www.zip-codes.com/area-code/area-code-564.asp
  5. https://www.areacodelocations.info/5/564.html
  6. https://www.utc.wa.gov/news/2025/utc-approves-new-564-area-code-206-region
  7. https://www.allareacodes.com/360
  8. https://www.fox13seattle.com/news/564-area-code-expands-seattle
  9. https://www.att.com/scmsassets/support/other/wa050125-629kb.pdf
  10. https://www.seattletimes.com/seattle-news/northwest/new-area-code-coming-for-western-washington-in-2017/
  11. https://www.utc.wa.gov/regulated-industries/utilities/telecommunications/washington-state-area-codes-and-numbering-issues
  12. https://www.peninsuladailynews.com/news/new-area-code-mandatory-10-digit-dialing-set-for-region/
  13. https://www.att.com/idpassets/images/support/pdf/WA-360-564-MandatoryWirelineSingPgTAG.pdf
  14. https://www.thecentersquare.com/washington/article_d506b90c-0ece-11ee-a886-d71ba292d832.html
  15. https://www.utc.wa.gov/news/2023/new-area-code-coming-seattle-area
  16. https://www.king5.com/article/news/local/10-digit-dialing-in-western-washington-starts-this-summer/281-393641462
  17. https://www.verizon.com/support/residential/homephone/area-international-info/area-code-lookup
  18. https://www.twilio.com/docs/glossary/what-area-code-overlay
  19. https://www.nanpa.com/sites/default/files/2024-10/2024-2_NPA_Exhaust_Projections_Final.pdf
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