Phone numbers in Sycamore, Illinois
Sycamore has 8 phone prefixes in area codes 779, 815.
Biggest holders: MetroPCS (T-Mobile), Frontier, Telnyx. This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 38%
- Local phone company 25%
- Internet / business phone carrier 38%
Every prefix in Sycamore
Search the first six digits of a number in this list. If it's here, the number started in Sycamore with the carrier shown. If it isn't, check the Illinois page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 779-222 | Telnyx | Internet / business phone carrier | – |
| 779-367 | Nuso | Internet / business phone carrier | 2023 |
| 779-759 | Onvoy | Internet / business phone carrier | 2021 |
| 815-739 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 815-895 | Frontier | Local phone company | – |
| 815-899 | Frontier | Local phone company | – |
| 815-970 | MetroPCS (T-Mobile) | Mobile carrier | 2002 |
| 815-991 | AT&T Mobility | Mobile carrier | – |
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.