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: 933

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-933 A Helena MT CLNCMTMARS1  9636 QWEST CORPORATION 648      
406-933 3 Helena MT   145J TERRA NOVA TELECOM INC. 648   2025-10-06   
406-933 5 Helena MT CLNCMTMARS1  9636 QWEST CORPORATION 648      
406-933 8 Helena MT CLNCMTMARS1  9636 QWEST CORPORATION 648      
406-933 9 Helena MT CLNCMTMARS1  9636 QWEST CORPORATION 648      

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

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