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: 304

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
231-304 A Brutus MI GDRPMIBL04Z  543C ONVOY, LLCV - MI 348      
231-304 1 Brutus MI GDRPMIBL04Z  543C ONVOY, LLCV - MI 348   2023-01-07   
231-304 3 Brutus MI GDRPMIBL36Z  624H ONVOY SPECTRUM, LLC 348   2021-06-18   
231-304 4 Brutus MI GDRPMIBL04Z  543C ONVOY, LLCV - MI 348   2020-12-26   
231-304 5 Brutus MI GDRPMIBL04Z  543C ONVOY, LLCV - MI 348   2020-12-26   
231-304 8 Brutus MI GDRPMIBL04Z  543C ONVOY, LLCV - MI 348   2022-03-04   
231-304 9 Brutus MI GDRPMIBL04Z  543C ONVOY, LLCV - MI 348   2023-08-12   

Last updated: Sun, 26 Jan 2025 15:59:20 UTC

Sponsored by: Callcentric - VoIP Internet phone service

Like this site? We accept donations via PayPal.