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: 503 [Rate centres in NPA 503] [Dial plan for NPA 503]

NXX: 634

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
503-634 A Monitor OR MNTRORXA0MD  2384 MONITOR COOP. TEL. CO. 672      

Last updated: Fri, 25 Jul 2025 03:21:23 UTC

Sponsored by: VoIP Much Phone Company

Like this site? We accept donations via PayPal.