Phone numbers in Nicasio, California
Nicasio has 11 phone prefixes in area codes 415, 628.
Biggest holders: Bandwidth, T-Mobile (including Sprint), Fractel. This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 18%
- Local phone company 9%
- Internet / business phone carrier 73%
Every prefix in Nicasio
Search the first six digits of a number in this list. If it's here, the number started in Nicasio with the carrier shown. If it isn't, check the California page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 415-323 | Bandwidth | Internet / business phone carrier | – |
| 415-598 | Bandwidth | Internet / business phone carrier | – |
| 415-630 | MCImetro (Verizon Business) | Internet / business phone carrier | – |
| 415-662 | AT&T (local phone) | Local phone company | – |
| 415-949 | Bandwidth | Internet / business phone carrier | 2014 |
| 415-997 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 628-204 | T-Mobile (including Sprint) | Mobile carrier | 2016 |
| 628-258 | T-Mobile (including Sprint) | Mobile carrier | 2017 |
| 628-293 | Commio | Internet / business phone carrier | 2023 |
| 628-356 | Fractel | Internet / business phone carrier | 2019 |
| 628-577 | Fractel | Internet / business phone carrier | 2021 |
Most prefixes are pooled: the 10,000 numbers in each are handed out in blocks of 1,000 to different carriers, and people can also take their numbers to another carrier. So the carrier shown is where the prefix started, not a guarantee about any one number. Source: NANPA central office code records, 2026-10-10.