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: 389

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-389 A Helena MT HLNAMTMAUMD  508J CENTURYLINK COMMUNICATIONS, LLC 648      
406-389 0 Helena MT   453F ONVOY, LLC - MT 648   2019-01-22   
406-389 1 Helena MT   453F ONVOY, LLC - MT 648   2019-01-22   
406-389 2 Helena MT   508J CENTURYLINK COMMUNICATIONS, LLC 648   2019-10-10   
406-389 3 Helena MT   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 648   2016-02-26   
406-389 4 Helena MT   453F ONVOY, LLC - MT 648   2021-07-05   
406-389 5 Helena MT   453F ONVOY, LLC - MT 648   2021-07-05   
406-389 6 Helena MT   453F ONVOY, LLC - MT 648   2021-07-05   
406-389 7 Helena MT   508J CENTURYLINK COMMUNICATIONS, LLC 648   2014-01-03   
406-389 8 Helena MT   453F ONVOY, LLC - MT 648   2019-01-22   
406-389 9 Helena MT   453F ONVOY, LLC - MT 648   2021-07-05   

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

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