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: 634

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-634 A Helena MT   453F ONVOY, LLC - MT 648      
406-634 3 Helena MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2020-09-06   
406-634 4 Helena MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2020-09-06   
406-634 5 Helena MT GRFLMTMA69Z  490J DISH WIRELESS, LLC 648   2023-08-21   

Last updated: Tue, 07 Oct 2025 16:47:53 UTC

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