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.

NPA: 312 [Rate centres in NPA 312] [Dial plan for NPA 312]

NXX: 221

NPA-NXX BLOCK Rate Centre Region Switch OCN LATA LIR Eff date Disc date
312-221 A Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358      
312-221 0 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-08   
312-221 1 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-08   
312-221 2 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-08   
312-221 3 Chicago Zone 01-Calumet IL ELGNILOTGT5  5562 METROPCS, INC. 358   2011-08-08   
312-221 4 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-08   
312-221 5 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-08   
312-221 6 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-08   
312-221 7 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-08   
312-221 8 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-09   
312-221 9 Chicago Zone 01-Calumet IL ELGNILOTGT5  6529 T-MOBILE USA, INC. 358   2011-08-08   

Last updated: Sun, 26 Jan 2025 15:59:20 UTC

Sponsored by: Callcentric - VoIP Internet phone service

Like this site? We accept donations via PayPal.