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: 227 [Rate centres in NPA 227] [Dial plan for NPA 227]

NXX: 312

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
227-312 A Washington Zone 11 MD   876D ONVOY, LLC - MD 236   2026-09-28   
227-312 0 Washington Zone 11 MD   876D ONVOY, LLC - MD 236   2026-09-28   
227-312 7 Washington Zone 11 MD   824J OPENTACT INC. 236   2026-10-16   

Last updated: Sat, 10 Oct 2026 15:24:20 UTC

Sponsored by: FiberConX Communications Ltd.

Like this site? We accept donations via PayPal.