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: 204

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
331-204 A Naperville IL CHCGIL24DS6  224C ONVOY, LLC 358      
331-204 0 Naperville IL   224C ONVOY, LLC 358   2016-02-11   
331-204 1 Naperville IL   224C ONVOY, LLC 358   2016-02-11   
331-204 2 Naperville IL   6534 NEW CINGULAR WIRELESS PCS, LLC - IL 358   2016-04-14   
331-204 3 Naperville IL   224C ONVOY, LLC 358   2016-05-01   
331-204 4 Naperville IL   224C ONVOY, LLC 358   2016-05-01   
331-204 5 Naperville IL   984E BANDWIDTH.COM CLEC, LLC - IL 358   2016-07-16   
331-204 6 Naperville IL   318J COMCAST IP PHONE, LLC 358   2016-10-17   
331-204 7 Naperville IL   073H TELNYX LLC 358   2017-03-17   
331-204 8 Naperville IL   515J IP HORIZON LLC 358   2016-08-09   
331-204 9 Naperville IL   6333 CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 358   2016-08-31   

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

Sponsored by: FiberConX Communications Ltd.

Like this site? We accept donations via PayPal.