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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San Mateo, CA

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NPA-NXX BLOCK Switch OCN LATA LIR Eff date Disc date

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Last updated: Wed, 18 Jun 2025 02:30:00 UTC

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