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: HLNAMTMAZMD

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
406-235 6 Wolf Creek MT 624H ONVOY SPECTRUM, LLC 648   2025-01-02   
406-417 2 Helena MT 624H ONVOY SPECTRUM, LLC 648   2025-01-02   
406-645 2 Deer Lodge MT 624H ONVOY SPECTRUM, LLC 648   2025-01-02   
406-865 1 Dillon MT 624H ONVOY SPECTRUM, LLC 648   2025-01-02   
406-980 5 Townsend MT 624H ONVOY SPECTRUM, LLC 648   2025-01-02   

Last updated: Sun, 07 Dec 2025 22:02:11 UTC

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