Local Calling Guide

Area code/prefix search

Search area code/prefix (NPA/NXX)
  • Effective date searches are available only for US area codes. Our sources for non-US NPA-NXX data do not provide this information.
  • If you want to search an entire area code regardless of activity, leave both the next and past days fields set to zero.

Switch: CHCGILMODS0

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
312-421 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 0 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 1 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 2 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 3 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 4 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 5 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 6 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 7 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-433 8 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-491 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-572 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-572 1 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-572 2 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-572 3 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-572 4 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-572 5 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-633 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-738 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-829 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-850 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-948 1 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358   2002-06-03   
312-948 2 Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358   2002-06-03   

Last updated: Tue, 04 May 2021 15:04:27 UTC

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