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: BLNGOKMARS1

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
580-725 A Billings OK 9533 SOUTHWESTERN BELL 536      
580-725 1 Billings OK 9533 SOUTHWESTERN BELL 536      
580-725 3 Billings OK 9533 SOUTHWESTERN BELL 536      

Last updated: Sun, 27 Apr 2025 12:48:38 UTC

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