Phone numbers in Lake Mills, Wisconsin
Lake Mills has 5 phone prefixes in area codes 274, 920.
Biggest holders: T-Mobile (including Sprint), Onvoy, Frontier. This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 40%
- Local phone company 20%
- Internet / business phone carrier 40%
Every prefix in Lake Mills
Search the first six digits of a number in this list. If it's here, the number started in Lake Mills with the carrier shown. If it isn't, check the Wisconsin page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 274-444 | Onvoy | Internet / business phone carrier | 2025 |
| 920-222 | T-Mobile (including Sprint) | Mobile carrier | – |
| 920-297 | T-Mobile (including Sprint) | Mobile carrier | – |
| 920-648 | Frontier | Local phone company | – |
| 920-945 | Charter / Spectrum | Internet / business phone carrier | 2006 |
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.