ONTARIO — CA
Data last updated: March 10, 2026
Area Codes
Top Carriers
| Carrier | OCN | NXX Count |
|---|---|---|
| FRONTIER CALIFORNIA INC. | 2319 | 21 |
| CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA | 6006 | 21 |
| NEW CINGULAR WIRELESS PCS, LLC | 6010 | 21 |
| METROPCS NETWORKS, LLC | 899D | 15 |
| T-MOBILE USA, INC. | 6529 | 9 |