Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
  • Effective date searches are available only for US area codes. Our sources for non-US NPA-NXX data do not provide this information.
  • If you want to search an entire area code regardless of activity, leave both the next and past days fields set to zero.

Switch: GRFLMTMAYMD

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
406-380 6 Lewistown MT 145J TERRA NOVA TELECOM INC. 648   2026-06-04   
406-560 9 Anaconda MT 145J TERRA NOVA TELECOM INC. 648   2026-06-05   
406-649 0 St Regis MT 145J TERRA NOVA TELECOM INC. 648   2025-10-11   
406-707 A Lewistown MT 145J TERRA NOVA TELECOM INC. 648      
406-825 4 Clinton MT 145J TERRA NOVA TELECOM INC. 648   2026-06-05   
406-865 6 Dillon MT 145J TERRA NOVA TELECOM INC. 648   2026-07-05   
406-879 8 Havre MT 145J TERRA NOVA TELECOM INC. 648   2026-07-05   
406-881 3 Olney MT 145J TERRA NOVA TELECOM INC. 648   2026-07-05   
406-933 4 Helena MT 145J TERRA NOVA TELECOM INC. 648   2026-06-05   
406-988 9 Dillon MT 145J TERRA NOVA TELECOM INC. 648   2025-10-11   

Last updated: Thu, 16 Jul 2026 02:21:55 UTC

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