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.

OCN: 453F ONVOY, LLC - MT

<< 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

NPA-NXX BLOCK Rate Centre Region Switch LATA LIR Eff date Disc date
406-991 4 Marion MT GRFLMTMA7MD  648   2019-09-15   
406-991 7 Marion MT GRFLMTMA7MD  648   2007-12-06   
406-991 8 Marion MT GRFLMTMA7MD  648   2011-03-05   
406-992 A Helena MT   648      
406-992 0 Helena MT   648   2025-05-17   

<< 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Last updated: Sun, 17 May 2026 03:26:51 UTC

Sponsored by: VoIP Much Phone Company

Like this site? We accept donations via PayPal.