Phone numbers in King City, California
King City has 7 phone prefixes in area code 831.
Biggest holders: AT&T (local phone), Onvoy, IP Horizon. This is the local calling area (rate center) where those prefixes were first assigned.
- Local phone company 29%
- Internet / business phone carrier 71%
Every prefix in King City
Search the first six digits of a number in this list. If it's here, the number started in King City with the carrier shown. If it isn't, check the California page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 831-263 | IP Horizon | Internet / business phone carrier | – |
| 831-385 | AT&T (local phone) | Local phone company | – |
| 831-386 | AT&T (local phone) | Local phone company | – |
| 831-387 | Bandwidth | Internet / business phone carrier | – |
| 831-525 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 831-830 | Onvoy | Internet / business phone carrier | 2020 |
| 831-931 | Onvoy | Internet / business phone carrier | 2023 |
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.