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: 531 [Rate centres in NPA 531] [Dial plan for NPA 531]

NXX: 400

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
531-400 A Columbus NE OMAHNENWXPX  549E ONVOY, LLC - NE 644      
531-400 0 Columbus NE   939H COMMIO, LLC 644   2022-12-18   
531-400 1 Columbus NE   624H ONVOY SPECTRUM, LLC 644   2021-10-31   
531-400 2 Columbus NE   624H ONVOY SPECTRUM, LLC 644   2021-10-31   
531-400 3 Columbus NE   3233 LEVEL 3 COMMUNICATIONS, LLC - NE 644   2023-03-06   
531-400 4 Columbus NE   549E ONVOY, LLC - NE 644   2021-05-07   
531-400 5 Columbus NE   549E ONVOY, LLC - NE 644   2021-05-07   
531-400 6 Columbus NE   549E ONVOY, LLC - NE 644   2021-05-07   
531-400 7 Columbus NE   6534 NEW CINGULAR WIRELESS PCS, LLC - IL 644   2022-03-19   
531-400 8 Columbus NE   624H ONVOY SPECTRUM, LLC 644   2021-07-18   
531-400 9 Columbus NE   073H TELNYX LLC 644   2022-03-01   

Last updated: Tue, 13 Jan 2026 21:50:02 UTC

Sponsored by: Callcentric - VoIP Internet phone service

Like this site? We accept donations via PayPal.