The area code 406 is located in Billings, Montana.
Area code 406 is the single area code for the entire state of Montana, including Billings, the state’s largest city. Centered in south‑central Montana along the Yellowstone River, Billings is a key commercial and travel hub for the region, with the sandstone Rimrocks framing the city. 406 was one of the original North American Numbering Plan codes assigned in 1947, and it still provides statewide coverage for both landlines and mobile phones. This wide reach makes 406 closely tied to Montana’s identity and everyday communication.
Major cities and communities covered by 406 include:
From Billings, 406 also serves nearby landmarks and destinations such as the Little Bighorn Battlefield National Monument and Pompeys Pillar National Monument, while statewide it covers gateways to Yellowstone and Glacier National Park. All of Montana is in the Mountain Time Zone, so phone calls within 406 follow the same time standard across the state. For anyone seeing a 406 phone number from Billings or beyond, it signals a Montana-based call or text with broad, statewide relevance.
“Area code 406 was established in 1947 and covers the entire state of Montana.” — North American Numbering Plan Administrator (NANPA)
“10-digit dialing is required in area code 406 due to the nationwide 988 change (effective Oct. 24, 2021).” — Federal Communications Commission (FCC)
In short, if you’re looking up the Billings, MT area code, 406 is the code you’ll see—historic, statewide, and still going strong.