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: 204

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-204 A Helena MT MSSLMTMA0MD  9415 LEVEL 3 COMMUNICATIONS, LLC - MT 648      
406-204 0 Helena MT   9415 LEVEL 3 COMMUNICATIONS, LLC - MT 648      
406-204 1 Helena MT   453F ONVOY, LLC - MT 648   2012-12-13   
406-204 2 Helena MT   453F ONVOY, LLC - MT 648   2012-12-13   
406-204 3 Helena MT   9415 LEVEL 3 COMMUNICATIONS, LLC - MT 648   2011-11-25   
406-204 4 Helena MT   9415 LEVEL 3 COMMUNICATIONS, LLC - MT 648      
406-204 5 Helena MT   453F ONVOY, LLC - MT 648   2012-12-13   
406-204 6 Helena MT   073H TELNYX LLC 648   2024-03-11   
406-204 7 Helena MT   453F ONVOY, LLC - MT 648   2012-12-13   
406-204 8 Helena MT   5562 METROPCS, INC. 648   2017-08-31   
406-204 9 Helena MT   5562 METROPCS, INC. 648   2017-08-31   

Last updated: Tue, 13 Jan 2026 21:50:02 UTC

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