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: 557 [Rate centres in NPA 557] [Dial plan for NPA 557]

NXX: 242

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
557-242 A St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2025-11-15   
557-242 0 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2025-11-15   
557-242 1 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2025-11-15   
557-242 2 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2025-11-15   
557-242 3 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2025-11-15   
557-242 4 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2026-03-14   
557-242 5 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2026-05-03   
557-242 7 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2026-05-03   
557-242 8 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2025-11-17   
557-242 9 St Louis MO STLSMOWQDS2  093F ONVOY, LLC - MO 520   2025-11-17   

Last updated: Tue, 01 Sep 2026 00:40:05 UTC

Sponsored by: Execulink Telecom

Like this site? We accept donations via PayPal.