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: 316

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
406-316 A Boulder MT HLNAMTMAX0X  7421 AT&T - LOCAL 648      
406-316 0 Boulder MT GRFLMTMAKMD  624H ONVOY SPECTRUM, LLC 648   2021-11-14   
406-316 1 Boulder MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2021-04-22   
406-316 2 Boulder MT GRFLMTMAKMD  624H ONVOY SPECTRUM, LLC 648   2021-07-18   
406-316 3 Boulder MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2020-06-05   
406-316 4 Boulder MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2020-11-08   
406-316 5 Boulder MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2021-05-15   
406-316 6 Boulder MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2021-08-28   
406-316 7 Boulder MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2021-10-11   
406-316 8 Boulder MT GRFLMTMA7MD  453F ONVOY, LLC - MT 648   2021-11-18   
406-316 9 Boulder MT HLNAMTMAX0X  7421 AT&T - LOCAL 648   2019-10-01   

Last updated: Sun, 26 Jan 2025 15:59:20 UTC

Sponsored by: FiberConX Communications Ltd.

Like this site? We accept donations via PayPal.