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: CHCGILMODS1

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
312-226 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-243 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-355 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-361 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-413 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-432 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-455 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-492 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-563 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-569 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-666 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-710 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-733 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-743 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-746 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-770 A Chicago Zone 01-Calumet IL 9329 AMERITECH ILLINOIS 358      
312-864 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-942 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-947 A Chicago Zone 01-Calumet IL 9329 AMERITECH ILLINOIS 358   2010-12-18   
312-996 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      
312-997 A Chicago Zone 01-Monroe IL 9329 AMERITECH ILLINOIS 358      

Last updated: Tue, 31 Dec 2019 02:37:20 UTC

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