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.

Detroit Zone 4, MI

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

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Last updated: Tue, 16 Jun 2026 00:09:45 UTC

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