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: 983 [Rate centres in NPA 983] [Dial plan for NPA 983]

NXX: 228

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
983-228 A Denver CO   6010 NEW CINGULAR WIRELESS PCS, LLC 656   2026-07-03   

Last updated: Sun, 17 May 2026 03:26:51 UTC

Sponsored by: ISP Telecom

Like this site? We accept donations via PayPal.