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: 231 [Rate centres in NPA 231] [Dial plan for NPA 231]

NXX: 376

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
231-376 A Twin Lake MI GDRPMIBL04Z  543C ONVOY, LLCV - MI 348      
231-376 0 Twin Lake MI WYNGMIKAGT2  6534 NEW CINGULAR WIRELESS PCS, LLC - IL 348   2024-12-09   
231-376 6 Twin Lake MI GDRPMIBL04Z  543C ONVOY, LLCV - MI 348   2021-09-03   
231-376 7 Twin Lake MI   145J TERRA NOVA TELECOM INC. 348   2025-07-12   

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

Sponsored by: LES.NET

Like this site? We accept donations via PayPal.