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Area code 406

Telephone area code for Montana, United States

Wikipedia contributorsAdapted for Fathomly · View authors
5 min read
Source updated March 11, 2026
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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.

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.

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

01Central office codes of communities

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

Watch videos about Area code 406Explainers and documentaries on YouTube (opens in a new tab)

Sources and credits

This article is adapted from the Wikipedia article “Area code 406”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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Related topics

List of North American Numbering Plan area codes

The North American Numbering Plan divides the territories of its members into geographic numbering plan areas (NPAs). Each NPA is identified by one or more numbering plan area codes (NPA codes, or area codes), consisting of three digits that are prefixed to each local telephone number having seven digits.