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.
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Switch: CHCGILIDDS0

NPA-NXX BLOCK Rate Centre Region OCN LATA LIR Eff date Disc date
312-222 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-229 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-229 2 Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-229 3 Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-229 8 Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-245 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-321 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-379 4 Chicago Zone 01-Calumet IL 9329 ILLINOIS BELL TEL CO 358   2000-05-05   
312-379 6 Chicago Zone 01-Calumet IL 9329 ILLINOIS BELL TEL CO 358   2000-05-05   
312-379 7 Chicago Zone 01-Calumet IL 9329 ILLINOIS BELL TEL CO 358   2000-05-05   
312-396 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-464 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-527 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-595 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-742 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-744 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-755 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-817 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-822 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-828 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-832 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-836 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-840 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-923 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-970 A Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-970 2 Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-970 3 Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-970 5 Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      
312-970 8 Chicago Zone 01-Illinois Dearborn IL 9329 ILLINOIS BELL TEL CO 358      

Last updated: Thu, 16 Oct 2025 03:04:18 UTC

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