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.

Switch: POWLWYMARS1

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
307-754 A Powell WY 9636 QWEST CORPORATION 654      
406-574 A Silvertip MT 9636 QWEST CORPORATION 654      
406-574 1 Silvertip MT 9636 QWEST CORPORATION 654      
406-574 3 Silvertip MT 9636 QWEST CORPORATION 654      

Last updated: Sun, 07 Dec 2025 22:02:11 UTC

Sponsored by: Callcentric - VoIP Internet phone service

Like this site? We accept donations via PayPal.