Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 231 [Rate centres in NPA 231] [Dial plan for NPA 231]

NXX: 306

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
231-306 A Cadillac MI GDRPMIBQ1MD  817J TELNET WORLDWIDE, INC. 348      

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

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