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: 331 [Rate centres in NPA 331] [Dial plan for NPA 331]

NXX: 400

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
331-400 A Oswego IL CHCGILWURMD  965H FRACTEL, LLC 358      
331-400 0 Oswego IL   965H FRACTEL, LLC 358   2019-10-02   
331-400 1 Oswego IL CHCGILWUDS4  063E PEERLESS NETWORK OF ILLINOIS, LLC - IL 358   2019-10-03   
331-400 2 Oswego IL CHCGIL24DS6  224C ONVOY, LLC 358   2021-08-12   
331-400 3 Oswego IL BURGILAHGT3  6534 NEW CINGULAR WIRELESS PCS, LLC - IL 358   2024-11-22   
331-400 4 Oswego IL   965H FRACTEL, LLC 358   2019-10-02   
331-400 5 Oswego IL CHCGIL24DS6  224C ONVOY, LLC 358   2024-04-05   
331-400 6 Oswego IL CHCGIL24DS6  224C ONVOY, LLC 358   2021-08-12   
331-400 7 Oswego IL CHCGIL24DS6  224C ONVOY, LLC 358   2021-08-12   
331-400 8 Oswego IL CHCGIL24XMD  495J STRATUS NETWORKS 358   2020-09-26   
331-400 9 Oswego IL   515J IP HORIZON LLC 358   2021-06-26   

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

Sponsored by: VoIP.ms

Like this site? We accept donations via PayPal.