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: CHCGILLRDS0

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
312-228 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-233 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-240 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-297 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-374 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-472 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358   2005-12-18   
312-540 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-552 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-565 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-616 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-653 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-729 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-819 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-856 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-861 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-938 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      
312-946 A Chicago Zone 01-Lakeshore IL 9329 AMERITECH ILLINOIS 358      

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

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