Phone numbers in Alta, California
Alta has 4 phone prefixes in area code 530.
Biggest holders: Teleport Communications America, AT&T (local phone), Onvoy. This is the local calling area (rate center) where those prefixes were first assigned.
- Local phone company 25%
- Internet / business phone carrier 50%
- Phone company 25%
Every prefix in Alta
Search the first six digits of a number in this list. If it's here, the number started in Alta with the carrier shown. If it isn't, check the California page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 530-388 | Teleport Communications America | Internet / business phone carrier | – |
| 530-389 | AT&T (local phone) | Local phone company | – |
| 530-464 | Onvoy | Internet / business phone carrier | – |
| 530-847 | AT&T Enterprises | Phone company | 2011 |
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.