HILLSDALE — IL
Data last updated: June 25, 2026
Area Codes
Top Carriers
| Carrier | OCN | NXX Count |
|---|---|---|
| CITIZENS TELECOM CO ILLINOIS-FRONTIER CITIZENS -IL | 1183 | 1 |
| MEDIACOM TELEPHONY OF ILLINOIS, LLC - IL | 846F | 1 |
Data last updated: June 25, 2026
| Carrier | OCN | NXX Count |
|---|---|---|
| CITIZENS TELECOM CO ILLINOIS-FRONTIER CITIZENS -IL | 1183 | 1 |
| MEDIACOM TELEPHONY OF ILLINOIS, LLC - IL | 846F | 1 |