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Area code 406
Area code 406
Area code 406
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Montana numbering plan area and area code (blue)

Area code 406 is the telephone area code in the North American Numbering Plan for the entire U.S. state of Montana. It has been Montana's only area code since the American Telephone and Telegraph Company created a nationwide telephone numbering plan in 1947.

As of 2013, 47 carriers served 1.7 million lines in Montana. All but two wireline providers support local number portability (the exceptions are small rural independents Hot Springs Telephone Company and Northern Telephone Cooperative). Sufficient available codes for new exchanges in the 406 area code exist to meet anticipated demand until 2031; number pooling has been implemented in response to increased demand and inefficient use of 406 numbering resources.[1][2]

Prior to October 2021, area code 406 had telephone numbers assigned for the central office code 988. In 2020, 988 was designated nationwide as a dialing code for the National Suicide Prevention Lifeline, which created a conflict for exchanges that permit seven-digit dialing. This area code was therefore scheduled to transition to ten-digit dialing by October 24, 2021.[3]

For many Montanans, area code 406 has become an unofficial symbol of the state.[4] Some Montanans celebrate April 6 as "406 Day," an unofficial holiday celebrating the state.[5]

Central office codes of communities

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Within the Montana numbering plan area, the following communities are served by the listed central office codes:

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Area code 406

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from Grokipedia
Area code 406 is the sole telephone area code serving the entire U.S. state of , encompassing all 56 counties and major cities including Billings, Missoula, Bozeman, Great Falls, and Helena.
Established on January 1, 1947, as one of the original 86 area codes in the (NANP) created by , it has remained the only code for the state without splits or overlays for nearly eight decades.
The code operates in the and supports both and services across Montana's diverse , from urban centers to rural areas.
In October 2021, Montana transitioned to mandatory 10-digit local dialing (including the 406 prefix) to accommodate the national suicide and crisis lifeline, preventing conflicts with existing 988 exchanges.
As of 2025, the 406 area code faces projected exhaustion of available numbers by early 2033 due to and increased demand for mobile and VoIP services, though the Montana Commission is pursuing optimization strategies, including rate center consolidation, to extend its usability without introducing a new overlay code.
Beyond its functional role, 406 has become a cultural symbol of Montana identity, often celebrated in local branding, businesses, and merchandise as a mark of state pride.

History

Establishment in 1947

The (NANP) was established in 1947 by the American Telephone and Telegraph Company () and Bell Laboratories to standardize telephone numbering and enable direct long-distance dialing across the , , and parts of the . This initiative addressed the growing demand for efficient toll calling following , replacing operator-assisted connections with a ten-digit system comprising a three-digit area code followed by a seven-digit local number. AT&T assigned 86 original area codes, known as numbering plan areas (NPAs), to geographic regions based on and existing telephone infrastructure, with most states receiving a single code to accommodate rotary dial technology that favored shorter dialing sequences for high-traffic areas. Area code 406 was one of these original assignments, designated specifically for the entire state of effective , 1947, due to the state's sparse population of approximately 560,000 residents and its vast rural landscape, which limited the scale of service. Montana's low —about 3.8 per —meant that infrastructure was underdeveloped compared to urban centers, with many exchanges relying on manual switchboards rather than automated systems. This single-area-code structure reflected the NANP's design for 34 states and provinces with minimal needs, avoiding the complexity of splits or overlays at the outset. Initially, 406 encompassed all telephone service in Montana without internal boundaries, serving both urban hubs like Billings and remote rural lines connected via party lines or magneto crank systems. Post-World War II expansion of the Bell System in Montana focused on extending basic rotary dial service to farms and small towns, where direct dialing was not yet widespread and operators handled most connections. The area's code facilitated seamless statewide and interstate calls, supporting economic growth in agriculture and mining without the immediate pressure for additional codes.

Number exhaustion projections and conservation

In 2013, area code 406 reached 88% utilization, prompting projections of exhaustion by 2018 and leading the Montana Public Service Commission (PSC) to implement conservation measures. By 2017, updated forecasts extended the area's usability to at least 2031 through number recycling and efficiency initiatives overseen by the PSC, averting earlier threats of depletion. Projections shifted again in 2022, forecasting exhaustion in late 2027 amid ongoing demand, though the PSC continued advocating for federal waivers to prioritize conservation over new codes. As of 2024, the Administrator () reported a revised exhaust date of the fourth quarter of 2028, based on Numbering Resource Utilization and Forecast (NRUF) data reflecting reduced historical demand but accelerating trends. In August 2025, the PSC approved rate center consolidation and other optimization strategies, extending the projected exhaustion to early 2033 and addressing population growth and mobile demand without introducing an overlay code. NANPA plays a central role in monitoring 406's status through quarterly NRUF reports and approving relief plans, consistently emphasizing measures that avoid overlays to maintain Montana's unique single-area-code identity. Key conservation efforts include mandatory unassigned number pooling, enacted by the PSC in 2013, which requires carriers to return sparsely used blocks (10% or less utilization) for redistribution, and rate center consolidation initiatives approved in 2025 to merge overlapping geographic areas for more efficient allocation.

Coverage

Geographic scope

Area code 406 encompasses the entirety of Montana, a state spanning 147,040 square miles, which positions it as one of the largest single-area-code jurisdictions within the North American Numbering Plan (NANP). This comprehensive territorial reach includes all 56 counties, extending from densely populated urban hubs to expansive rural landscapes and sovereign tribal lands, without any overlays, splits, or exclusions that fragment the numbering plan across the state. As a result, 406 remains one of only a handful of area codes serving an entire U.S. state undivided, a status shared by just 10 others as of 2025, including Alaska, Delaware, Hawaii, Maine, New Hampshire, North Dakota, Rhode Island, South Dakota, Vermont, and Wyoming. The state's alignment with the Mountain Time Zone further unifies its geographic and temporal scope, as every location within Montana's borders observes Mountain Standard Time (MST) during standard periods and Mountain Daylight Time (MDT) during daylight saving, with no deviations or overlaps into adjacent zones like Pacific Time. This uniformity simplifies telecommunications across the region, contrasting sharply with more populous or compact states that underwent early area code divisions—such as , which split its original code in the due to rapid growth in a much smaller 163,696-square-mile footprint. Montana's vast size, combined with its relatively low , has preserved this singular code structure; with approximately 1.14 million residents as of July 1, 2024, spread thinly over rugged terrain including the and , the demand for telephone numbers has historically been modest enough to delay the need for relief measures. This geographic exclusivity underscores 406's role in supporting 's diverse economic and social fabric, from in the eastern prairies to in western national parks, all under a single dialing prefix that reflects the state's interconnected yet expansive identity.

Major cities and counties

Area code 406 serves the entire state of , encompassing all 56 counties and a total of approximately 1.14 million residents as of July 1, 2024. The state's is unevenly distributed, with higher concentrations in western and central urban areas and greater sparsity in the rural east, influencing communication patterns through concentrated in centers. The largest city within the area code is Billings in Yellowstone County, with a population of 120,797 as of July 1, 2024, serving as the economic hub for through sectors like production, healthcare, and agriculture-related commerce. Missoula, in Missoula County, follows with 77,647 residents, functioning as a key university town anchored by the and supporting education, healthcare, and retail services. Great Falls, located in Cascade County, has a population of 60,013 and acts as a central agricultural and distribution center, bolstered by and manufacturing. Bozeman in Gallatin County, with 57,106 residents, has experienced rapid growth driven by technology startups, , and tourism tied to . Helena, the state capital in Lewis and Clark County, rounds out the top five with 34,369 residents, primarily sustaining government administration, legal services, and tourism around historical sites. Other notable cities include Butte-Silver Bow in Deer Lodge County (36,134 residents), historically centered on mining but now focusing on education via and ; Kalispell in Flathead County (31,296 residents), a gateway for near Glacier National Park with emphasis on healthcare and retail; Havre in Hill County (9,333 residents), supporting agriculture and rail transportation as a northern rail hub; and Miles City in Custer County (8,413 residents), known for ranching, energy extraction, and events like the Miles City Sale. The area code covers all Montana counties, grouped regionally: western counties like Missoula, Flathead, and Ravalli emphasize tourism, forestry, and education; central counties such as Cascade, Lewis and Clark, and Meagher focus on , , and activities; eastern counties including Yellowstone, Big Horn, and Rosebud support energy, ranching, and manufacturing; and northern counties like Hill, , and Blaine feature and tribal economies. This includes significant tribal lands, such as the Blackfeet Indian Reservation in County and the Crow Reservation in Big Horn County, where economic activities blend traditional practices with modern and . Economically, the region relies on agriculture for rural connectivity needs, energy production in eastern counties for industrial communications, and tourism in western areas for seasonal usage spikes, shaping overall telephone infrastructure demands across these diverse population centers.
CityCountyPopulation as of July 1, 2024Primary Economic Role
BillingsYellowstone120,797Energy, healthcare, agriculture hub
MissoulaMissoula77,647Education, retail, healthcare
Great FallsCascade60,013Agriculture, military, manufacturing
BozemanGallatin57,106Technology, tourism, education
HelenaLewis and Clark34,369Government, administration
Butte-Silver BowDeer Lodge36,134Mining heritage, education
KalispellFlathead31,296Tourism, healthcare
HavreHill9,333Agriculture, rail
Miles CityCuster8,413Ranching, energy

Cultural significance

State identity and symbolism

Area code 406 has evolved into a powerful symbol of Montanan pride and identity since the late , transcending its original role as a telephone numbering designation to embody the state's and vast landscapes. By the , as Montana's population grew modestly without necessitating a split, the code began appearing in local branding efforts, such as apparel and merchandise that celebrated "Big Sky Country" ethos. This trend accelerated in the , with approximately 400 businesses incorporating "406" into their names by 2019 and over 1,900 active entities using it for marketing by 2025, highlighting its role in fostering a unified state identity. In media and popular culture, 406 frequently references Montana's open spaces and self-reliant spirit, appearing in local , advertisements, and narratives that reinforce its emblematic status. For instance, discussions around technology integrations, such as early VoIP services in the late , sparked conversations about preserving the code's cultural resonance amid digital shifts. Unlike densely packed urban codes like New York's 212, which symbolize cosmopolitan hustle, 406 evokes the expansive freedom of Montana's 147,000 square miles covered by a single overlay-free zone. Preservation efforts underscore 406's integral place in Montanan uniqueness, with public opposition to proposed splits or overlays voiced during Public Service Commission (PSC) hearings as far back as the early 2000s. In 2022, PSC commissioners emphasized in a letter to the that "the 406 area code is a symbol of pride and identity to the people of ," advocating for conservation measures to delay exhaustion projected around 2027. This sentiment persists, as seen in 2025 PSC discussions where adding a second code was deemed controversial, prompting strategies like number pooling to prolong its use without fragmentation. Amid ongoing exhaustion projections shifting to early 2033, 2025 has seen renewed campaigns and regulatory focus to "extend the 406," reinforcing its status as a cultural touchstone through initiatives that prioritize state unity over expansion. Annual 406 Day events briefly highlight this symbolism in community gatherings.

406 Day celebrations

406 Day is an unofficial observed annually on in , corresponding to the date 4/06, to celebrate the state's singular area code, 406, which unifies the fourth-largest state by land area despite its sparse population. This observance highlights Montana's unique status as one of only 11 U.S. states with a single area code, symbolizing connectivity across its vast 94 million acres. While the exact origins trace back to informal recognitions in the early , it has evolved into a statewide expression of local pride without formal establishment as a legal . Celebrations typically involve community-driven activities that emphasize Montana's outdoor lifestyle and local economy, such as in national forests, visiting state parks like , or exploring landmarks including Yellowstone and Glacier National Parks. Participants often support homegrown businesses through purchases of 406-themed merchandise, including t-shirts, ornaments, and decals available from local retailers. plays a central role, with campaigns under #406Day encouraging users to post photos of Montana's landscapes, , and daily life, fostering a "406 challenge" tradition of sharing personal connections to the state. By 2025, the event has grown into a broadly recognized occasion across major cities like Billings, Missoula, and Helena, drawing participation from residents, businesses, and visitors to enhance state identity and stimulate tourism through special promotions at breweries and outfitters. Common ways to join include enjoying Montana-brewed beers, donating to conservation causes, or simply embracing the "Big Sky Country" ethos with family outings. These gatherings, often featuring live music or casual meetups, underscore the area code's role in promoting awareness of history and number conservation efforts by the Commission.

Technical details

Central office codes

Central office codes, also known as NXX prefixes, are the three-digit codes (ranging from 200 to 999, excluding certain restricted combinations) that identify specific local telephone exchanges or rate centers within area code 406. These codes form the middle portion of a ten-digit phone number and route calls to particular communities or service areas across . In the , area code 406 originally had up to 800 possible NXX codes available, though practical assignments have historically been around 792 after accounting for early restrictions on N0X and N1X formats; by 2024, approximately 752 NXX codes were assigned to support , , and VoIP services statewide. These assignments are distributed among approximately 250 rate centers, reflecting Montana's sparse population and vast geography. The allocation and management of these NXX codes in area code 406 are overseen by the Administrator () and implemented by local exchange carriers, including CenturyLink (formerly ), Blackfoot Communications, and wireless providers such as Verizon Wireless and . To address growing demand and prevent waste, thousands-block number pooling has been in place since the early 2000s, allowing carriers to share unused portions of NXX blocks rather than holding entire prefixes idle. Key NXX assignments are tied to major urban centers, where multiple prefixes support high call volumes, while rural areas often share codes across broader rate centers. For example, Billings utilizes over 20 NXX codes, including 206 for services and 208 for . Missoula features assignments like 203 and 214, Great Falls includes 217 and 268, Bozeman has 404 and 414, and Helena employs the 44x series such as 475 and 634. The following table summarizes select active NXX codes for prominent cities, based on carrier assignments:
CityExample NXX CodesPrimary Usage TypeCarrier Examples
Billings200, 206, 208, 325, 534, 617, 620, 657, 702, 876Landline, WirelessCenturyLink, Verizon Wireless,
Missoula203, 207, 214, 481, 532, 610, 721, 830Landline, WirelessCenturyLink, Onvoy LLC,
Great Falls205, 217, 231, 268, 452, 727, 761, 771, 791, 878Landline, WirelessCenturyLink, Verizon Wireless
Bozeman209, 404, 414, 451, 522, 539, 556, 570, 577, 613, 994Landline, Wireless, , Bandwidth.com
Helena202, 204, 324, 442, 449, 475, 594, 634, 841Landline, WirelessCenturyLink,
In rural communities, NXX codes are frequently shared among nearby towns to maximize efficiency; for instance, prefixes like 875 serve both Pompeys Pillar and surrounding areas, while smaller rate centers such as Forsyth or may rely on a single shared NXX like 201 or 612. Urban areas like Helena, with its dedicated 44x series, contrast this by maintaining multiple distinct prefixes to handle denser populations and diverse carrier needs.

Dialing procedures and current status

Within the 406 area code, all local calls require 10-digit dialing, consisting of the area code followed by the seven-digit telephone number, a mandate effective since October 24, 2021, to support the nationwide 988 suicide and crisis lifeline and align with North American Numbering Plan (NANP) standards introduced in the 1990s. This procedure applies universally across Montana, with no modifications as of November 2025. For long-distance calls to 406 numbers from outside or internationally within the NANP, the standard format is the international prefix (if applicable), followed by 1 + 406 + the seven-digit number. As of December 31, 2023, area code 406 had approximately 40.6% of its numbering resources assigned, leaving about 54.6% available amid steady demand driven by and in-migration, particularly in urban centers like Bozeman and Missoula. Major carriers including Verizon and provide wireline and wireless services, while VoIP providers such as and have increasingly integrated into the pool, contributing to efficient through thousands-block number pooling. No overlay is planned in the immediate term, though the Public Service Commission continues to monitor utilization and pursue conservation strategies, such as rate center consolidation, with projections indicating viability through at least early 2033 and potential extensions beyond if measures succeed.

References

  1. https://directory.mt.gov/govt/state-dir/index
  2. https://www.areacodelocations.info/4/406.html
  3. https://www.allareacodes.com/406
  4. https://talkroute.com/virtual-phone-numbers/local-phone-numbers/montana-phone-numbers/
  5. https://www.sent.dm/resources/area-code-406
  6. https://www.psc.mt.gov/News/2021/10-digit-dialing
  7. https://psc.mt.gov/News/2022/news-article1
  8. https://www.bozemandailychronicle.com/news/the-406-area-code-is-running-out-of-room-but-a-new-strategy-is-likely/article_9cdff06d-7fec-5c55-be0c-1848aadc67aa.html
  9. https://www.montanarightnow.com/helena/406-more-than-just-an-area-code/article_20dc2d9c-e7ca-11e9-b7db-8b45e61949a8.html
  10. https://docs.fcc.gov/public/attachments/DOC-408489A1.pdf
  11. https://www.bandwidth.com/glossary/number-planning-area-npa/
  12. https://www.lincmad.com/table1947.html
  13. https://www.helenahistory.org/telephone-history.htm
  14. https://bozemanmagazine.com/articles/2019/12/31/103430-wires-in-the-sky-a-short-history-of-telephone
  15. https://www.greatfallstribune.com/story/news/2017/11/27/406-area-code-in-montana-extended/898459001/
  16. https://missoulacurrent.com/406-area-code/
  17. https://www.nanpa.com/sites/default/files/2024-10/2024-2_NPA_Exhaust_Projections_Final.pdf
  18. https://helenair.com/news/state-regional/government-politics/article_8825ebd6-a695-46b0-8974-7343fc62a196.html
  19. https://msl.mt.gov/geoinfo/geography/geography_facts/area_of_montana_counties
  20. https://www.census.gov/geographies/reference-files/2010/geo/state-local-geo-guides-2010/montana.html
  21. https://www.calilio.com/blogs/states-with-only-one-area-code
  22. https://www.timetemperature.com/tzus/montana_time_zone.shtml
  23. https://www.census.gov/geographies/reference-files/2010/geo/state-area.html
  24. https://www.census.gov/data/tables/time-series/demo/popest/2020s-state-total.html
  25. https://montanafreepress.org/2025/06/04/montana-population-growth-slows-though-some-hot-spots-remain/
  26. https://www.montana-demographics.com/kalispell-demographics
  27. https://www.montana-demographics.com/havre-demographics
  28. https://www2.census.gov/programs-surveys/popest/tables/2020-2024/cities/totals/SUB-IP-EST2024-POP-30.xlsx
  29. https://www.zip-codes.com/area-code/area-code-406.asp
  30. https://www.britannica.com/place/Montana-state/Economy
  31. https://montanafreepress.org/2018/11/17/where-the-jobs-are-montanas-economic-landscape-visualized/
  32. https://www.kulr8.com/news/montana/406-more-than-just-an-area-code/video_5a719364-ea1b-11e9-9566-8303fd00043e.html
  33. https://helenair.com/news/state-regional/life-in-the-406-facts-behind-montanas-iconic-area-code/collection_08889199-25d0-5478-8257-6a23e729816e.html
  34. https://billingsgazette.com/news/state-regional/article_0342a35e-745c-5f41-88eb-8aaf9d1f4e95.html
  35. https://www.ktvh.com/news/montana-psc-looks-for-ways-to-extend-life-of-406-area-code
  36. https://www.krtv.com/news/montana-and-regional-news/montana-is-celebrated-on-406-day
  37. https://www.giftcorral.com/blogs/montana-gift-corral-blog/what-is-406-day
  38. https://www.thearmorylife.com/forum/threads/happy-406-day.22283/
  39. https://www.redbubble.com/shop/406%2Bmontana
  40. https://www.youtube.com/watch?v=dpqu40o1WLg
  41. https://www.visitbigsky.com/articles/post/celebrating-406-day-find-your-big-sky-adventure/
  42. https://z100missoula.com/celebrate-montana-406-day/
  43. https://localcallingguide.com/lca_listexch.php?npa=406
  44. https://www.telcodata.us/search-area-code-exchange-detail?npa=406&exchange=624
  45. https://localcallingguide.com/lca_prefix.php?npa=406
  46. https://www.wirefly.com/area-codes/montana/billings
  47. https://www.wirefly.com/area-codes/montana/missoula
  48. https://www.wirefly.com/area-codes/montana/great-falls
  49. https://www.wirefly.com/area-codes/montana/bozeman
  50. https://www.wirefly.com/area-codes/montana/helena
  51. https://www.nanpa.com/sites/default/files/2025-04/2025-1NPAExhaustProjectionsFinal.pdf
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