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: 400

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-400 A Havre MT HAVRMTXCDS1  958H TRIANGLE COMMUNICATION SYSTEM, INC. - MT- 648      
406-400 0 Havre MT   453F ONVOY, LLC - MT 648   2017-07-31   
406-400 1 Havre MT   453F ONVOY, LLC - MT 648   2017-07-31   
406-400 2 Havre MT   958H TRIANGLE COMMUNICATION SYSTEM, INC. - MT- 648   2017-06-18   
406-400 3 Havre MT   453F ONVOY, LLC - MT 648   2017-07-31   
406-400 4 Havre MT   453F ONVOY, LLC - MT 648   2017-07-31   
406-400 5 Havre MT   453F ONVOY, LLC - MT 648   2017-07-31   
406-400 6 Havre MT   453F ONVOY, LLC - MT 648   2017-07-31   
406-400 7 Havre MT   453F ONVOY, LLC - MT 648   2017-07-31   
406-400 8 Havre MT   453F ONVOY, LLC - MT 648   2017-07-31   
406-400 9 Havre MT   453F ONVOY, LLC - MT 648   2017-09-18   

Last updated: Thu, 29 Jan 2026 14:35:03 UTC

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