Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
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Chicago Zone 01-Monroe, IL

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NPA-NXX BLOCK Switch OCN LATA LIR Eff date Disc date
312-666 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-710 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-733 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-738 A CHCGILMODS0  9329 ILLINOIS BELL TEL CO 358      
312-743 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-743 0   9329 ILLINOIS BELL TEL CO 358      
312-743 1   9329 ILLINOIS BELL TEL CO 358      
312-743 2   9329 ILLINOIS BELL TEL CO 358      
312-743 3   9329 ILLINOIS BELL TEL CO 358      
312-743 4   9329 ILLINOIS BELL TEL CO 358      
312-743 5   9329 ILLINOIS BELL TEL CO 358      
312-743 6   9329 ILLINOIS BELL TEL CO 358      
312-743 7   9329 ILLINOIS BELL TEL CO 358      
312-743 8   9329 ILLINOIS BELL TEL CO 358      
312-743 9   9329 ILLINOIS BELL TEL CO 358      
312-746 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-829 A CHCGILMODS0  9329 ILLINOIS BELL TEL CO 358      
312-850 A CHCGILMODS0  9329 ILLINOIS BELL TEL CO 358      
312-864 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-894 A BNSVILDGDS0  7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 0   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 1   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 2   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 3   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 4   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 5   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 6   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 7   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 8   7229 MCIMETRO ACCESS TRANSMISSION SERVICES LLC 358      
312-894 9   6534 NEW CINGULAR WIRELESS PCS, LLC - IL 358   2011-08-07   
312-942 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-996 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-997 A CHCGILMODS1  9329 ILLINOIS BELL TEL CO 358      
312-997 0   9329 ILLINOIS BELL TEL CO 358      
312-997 1   9329 ILLINOIS BELL TEL CO 358      
312-997 2   9329 ILLINOIS BELL TEL CO 358      
312-997 3   9329 ILLINOIS BELL TEL CO 358      
312-997 4   9329 ILLINOIS BELL TEL CO 358      
312-997 5   6115 LEVEL 3 COMMUNICATIONS, LLC - IL 358   2014-05-03   
312-997 6   9329 ILLINOIS BELL TEL CO 358      
312-997 7   9329 ILLINOIS BELL TEL CO 358      
312-997 8   9329 ILLINOIS BELL TEL CO 358      
312-997 9   9329 ILLINOIS BELL TEL CO 358      

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Last updated: Thu, 01 Jan 2026 03:59:49 UTC

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