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.

NPA: 571 [Rate centres in NPA 571] [Dial plan for NPA 571]

NXX: 743

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
571-743 A Herndon VA   138E ONVOY, LLC - VA 236   2025-12-26   
571-743 0 Herndon VA   138E ONVOY, LLC - VA 236   2025-12-26   

Last updated: Sun, 07 Dec 2025 22:02:11 UTC

Sponsored by: BeeVox - Whitelabel Reseller Platform

Like this site? We accept donations via PayPal.