Area Code 406-378 located in BIG SANDY, CHOUTEAU, MT, more detail is as below. Place NPA (Numbering Plan Area) : 406 NXX (Local Number Prefix) : 378 City : BIG SANDY County : CHOUTEAU State : MT (Montana) NXX Use Type : Landline NXX Intro Version : 1994-02-04 FIPS (Federal Information Processing Standards) : 30015 LATA (Local Access Transport Area) : 648 Rate Center : BIG SANDY ZIP Code Count : 522 ZIP Code Frequency : 96 ZIP Code : 59520 Other Information NPANXX : 406378 Switch CLLI (Common Language Location Identifier) : BGSNMTXCRS1 Time Zone : Mountain (GMT -07:00) Observes Daylight Saving Time : Yes Company : TRIANGLE TELEPHONE COOPERATIVE ASSN., INC. OCN (Operating Company Number) : 2257 Coverage Area Name : BIG SANDY Latitude : 48.1753 Longitude : -110.1072 ‹ previous : 406-378 next › : 406-379 Telephone Number List 406-378-0000 ~ 406-378-9999