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: DLLSOR58DS1

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
503-623 A Dallas OR 9638 QWEST CORPORATION 672      
503-831 A Dallas OR 9638 QWEST CORPORATION 672      

Last updated: Thu, 01 Jan 2026 03:59:49 UTC

Sponsored by: ISP Telecom

Like this site? We accept donations via PayPal.