SIERRAMADR — CA
Data last updated: March 10, 2026
Area Codes
Top Carriers
| Carrier | OCN | NXX Count |
|---|---|---|
| FRONTIER CALIFORNIA INC. | 2319 | 5 |
| T-MOBILE USA, INC. | 6529 | 2 |
| SKYE TELECOM LLC DBA SKYETEL | 622J | 1 |
| ONVOY, LLC - CA | 649C | 1 |
| U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | 1 |