| Prefix | City |
|---|---|
| 820-200 | Thousand Oaks, California |
| 820-201 | Oxnard, California |
| 820-222 | Camarillo, California |
| 820-300 | Guadalupe, California |
| 820-333 | Thousand Oaks, California |
| 820-400 | Parkfield, California |
| 820-444 | Newbury Park, California |
| 820-666 | San Luis Obispo, California |
| 820-777 | Santa Paula, California |
| 820-888 | Simi Valley, California |
| 820-999 | Oxnard, California |