Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 406 [Rate centres in NPA 406] [Dial plan for NPA 406]

NXX: 617

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-617 A Billings MT BLNGMTMAMMD  6010 NEW CINGULAR WIRELESS PCS, LLC 650   2025-02-16   
406-617 0 Billings MT BLNGMTMAX6X  732J NUSO, LLC 650   2025-02-17   
406-617 1 Billings MT BLNGMTMAX6X  732J NUSO, LLC 650   2025-02-17   
406-617 2 Billings MT BLNGMTMAXMD  6529 T-MOBILE USA, INC. 650   2025-04-05   
406-617 3 Billings MT BLNGMTMAXMD  6529 T-MOBILE USA, INC. 650   2025-08-07   
406-617 4 Billings MT BLNGMTMAXMD  6529 T-MOBILE USA, INC. 650   2025-07-08   
406-617 5 Billings MT BLNGMTMAXMD  6529 T-MOBILE USA, INC. 650   2025-07-08   
406-617 6 Billings MT BLNGMTMAXMD  6529 T-MOBILE USA, INC. 650   2025-06-14   
406-617 7 Billings MT BLNGMTWE9MD  073H TELNYX LLC 650   2025-02-17   
406-617 8 Billings MT BLNGMTMAMMD  6010 NEW CINGULAR WIRELESS PCS, LLC 650   2025-02-16   
406-617 9 Billings MT BLNGMTMAXMD  6529 T-MOBILE USA, INC. 650   2026-03-02   

Last updated: Sat, 01 Aug 2026 03:19:33 UTC

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