CHICGOZN01 — IL
Data last updated: August 31, 2026
Area Codes
Top Carriers
| Carrier | OCN | NXX Count |
|---|---|---|
| ILLINOIS BELL TEL CO | 9329 | 340 |
| NEW CINGULAR WIRELESS PCS, LLC - IL | 6534 | 101 |
| T-MOBILE USA, INC. | 6529 | 91 |
| CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL | 6333 | 87 |
| SPOK, INC. | 6630 | 42 |