Phone numbers in Belvidere, Illinois
Belvidere has 10 phone prefixes in area codes 779, 815.
Biggest holders: Nuso, Level 3 (Lumen), Frontier. This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 10%
- Local phone company 20%
- Internet / business phone carrier 50%
- Phone company 20%
Every prefix in Belvidere
Search the first six digits of a number in this list. If it's here, the number started in Belvidere with the carrier shown. If it isn't, check the Illinois page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 779-330 | Nuso | Internet / business phone carrier | 2021 |
| 779-359 | Nuso | Internet / business phone carrier | 2022 |
| 779-552 | Digital Network Access Communications | Phone company | 2007 |
| 815-323 | Level 3 (Lumen) | Internet / business phone carrier | 2005 |
| 815-544 | Frontier | Local phone company | – |
| 815-547 | Frontier | Local phone company | – |
| 815-566 | Level 3 (Lumen) | Internet / business phone carrier | 2002 |
| 815-604 | Onvoy | Internet / business phone carrier | 2019 |
| 815-912 | Aero North Communications | Phone company | 2001 |
| 815-975 | AT&T Mobility | Mobile carrier | 2002 |
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.