Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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NPA: 312 [Rate centres in NPA 312] [Dial plan for NPA 312]

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NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
312-999 8 Chicago Zone 01-Calumet IL CHCGILWBXDZ  984E BANDWIDTH.COM CLEC, LLC - IL 358   2011-08-14   
312-999 9 Chicago Zone 01-Calumet IL CHCGILWUX6X  460K FIRST COMMUNICATIONS, LLC 358   2014-01-02   

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Last updated: Wed, 18 Jun 2025 02:30:00 UTC

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