Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 557 [Rate centres in NPA 557] [Dial plan for NPA 557]

NXX: 258

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
557-258 A Oakville MO   093F ONVOY, LLC - MO 520   2026-08-29   
557-258 0 Oakville MO   093F ONVOY, LLC - MO 520   2026-08-29   

Last updated: Thu, 16 Jul 2026 02:21:55 UTC

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