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: DRBYMTMARS1

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
406-821 A Darby MT 9636 QWEST CORPORATION 648      
406-821 0 Darby MT 9636 QWEST CORPORATION 648      
406-821 1 Darby MT 9636 QWEST CORPORATION 648      
406-821 2 Darby MT 9636 QWEST CORPORATION 648      
406-821 3 Darby MT 9636 QWEST CORPORATION 648      
406-821 4 Darby MT 9636 QWEST CORPORATION 648      
406-821 9 Darby MT 9636 QWEST CORPORATION 648      

Last updated: Sat, 15 Nov 2025 03:38:44 UTC

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