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: DTTNMTMARS1

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
406-476 A Dutton MT 9636 QWEST CORPORATION 648      
406-476 3 Dutton MT 9636 QWEST CORPORATION 648      

Last updated: Sat, 02 May 2026 12:20:53 UTC

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