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.

Switch: DLLSTX97XFX

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
945-277 A Dallas TX 436J HADLO TECHNOLOGIES, LLC 552      
945-277 9 Dallas TX 436J HADLO TECHNOLOGIES, LLC 552   2023-07-07   

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

Sponsored by: ISP Telecom

Like this site? We accept donations via PayPal.