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.

Chicago Zone 01-Superior, IL

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NPA-NXX BLOCK Switch OCN LATA LIR Eff date Disc date
312-988 6 CHCGILSUDS2  9329 ILLINOIS BELL TEL CO 358      
312-988 7 CHCGILSUDS2  9329 ILLINOIS BELL TEL CO 358      
312-988 8 CHCGILSUDS2  9329 ILLINOIS BELL TEL CO 358      
312-988 9 CHCGILSUDS2  9329 ILLINOIS BELL TEL CO 358      

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Last updated: Sat, 04 Jul 2026 13:07:56 UTC

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