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.
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OCN: 016G TELSTAR COMMUNICATIONS INC

NPA-NXX BLOCK Rate Centre Region Switch LATA LIR Eff date Disc date
720-658 A Denver CO WNDSCODCCM0  656      
970-600 A Windsor CO WNDSCODCCM0  656      

Last updated: Thu, 29 Jan 2026 14:35:03 UTC

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