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.

OCN: 2384 MONITOR COOP. TEL. CO.

NPA-NXX BLOCK Rate Centre Region Switch LATA LIR Eff date Disc date
503-634 A Monitor OR MNTRORXA0MD  672      

Last updated: Sat, 15 Nov 2025 03:38:44 UTC

Sponsored by: Callcentric - VoIP Internet phone service

Like this site? We accept donations via PayPal.