Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
  • Effective date searches are available only for US area codes. Our sources for non-US NPA-NXX data do not provide this information.
  • If you want to search an entire area code regardless of activity, leave both the next and past days fields set to zero.

NPA: 406 [Rate centres in NPA 406] [Dial plan for NPA 406]

NXX: 943

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-943 A Sidney MT BLNGMTWE6MD  9415 LEVEL 3 COMMUNICATIONS, LLC - MT 650      
406-943 0 Sidney MT BLNGMTWE6MD  9415 LEVEL 3 COMMUNICATIONS, LLC - MT 650      
406-943 1 Sidney MT BLNGMTAS9MD  453F ONVOY, LLC - MT 650   2021-03-07   
406-943 2 Sidney MT BLNGMTAS9MD  453F ONVOY, LLC - MT 650   2021-03-07   
406-943 3 Sidney MT BLNGMTWEAMD  7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 650   2016-11-28   
406-943 4 Sidney MT BLNGMTWE6MD  9415 LEVEL 3 COMMUNICATIONS, LLC - MT 650      
406-943 5 Sidney MT BLNGMTWEBMD  771G TELEPORT COMMUNICATIONS AMERICA MT - LLC 650   2015-02-25   
406-943 6 Sidney MT BLNGMTAS9MD  453F ONVOY, LLC - MT 650   2020-11-10   
406-943 7 Sidney MT BLNGMTWE8MD  508J CENTURYLINK COMMUNICATIONS, LLC 650   2016-08-12   
406-943 8 Sidney MT BLNGMTAS9MD  453F ONVOY, LLC - MT 650   2021-07-05   
406-943 9 Sidney MT BLNGMTAS9MD  453F ONVOY, LLC - MT 650   2021-07-05   

Last updated: Wed, 18 Jun 2025 02:30:00 UTC

Sponsored by: Callcentric - VoIP Internet phone service

Like this site? We accept donations via PayPal.