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]

NXX: 679

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
312-679 A Chicago Zone 01-Calumet IL   671J U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 358   2026-03-31   
312-679 4 Chicago Zone 01-Calumet IL   671J U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 358   2026-03-31   
312-679 5 Chicago Zone 01-Calumet IL   671J U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 358   2026-03-31   

Last updated: Wed, 04 Mar 2026 03:00:52 UTC

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