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.

Washington Zone 13, MD

<< 1 2 3 4 5 6 >>

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

<< 1 2 3 4 5 6 >>

Last updated: Thu, 16 Oct 2025 03:04:18 UTC

Sponsored by: ISP Telecom

Like this site? We accept donations via PayPal.