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: 443 [Rate centres in NPA 443] [Dial plan for NPA 443]

NXX: 638

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
443-638 A Ellicott City MD BLTMMDDN4MD  2554 GLOBAL NAPS SOUTH, INC. - MD 238      

Last updated: Sun, 01 Jun 2025 02:18:11 UTC

Sponsored by: LES.NET

Like this site? We accept donations via PayPal.