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: 256

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
557-256 A Mehlville MO   093F ONVOY, LLC - MO 520   2026-07-20   
557-256 0 Mehlville MO   093F ONVOY, LLC - MO 520   2026-07-20   
557-256 1 Mehlville MO   093F ONVOY, LLC - MO 520   2026-07-20   

Last updated: Tue, 16 Jun 2026 00:09:45 UTC

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