Phone numbers in Baldwin, Michigan
Baldwin has 5 phone prefixes in area code 231.
Biggest holders: Bandwidth, Interactive Services Network, 123.NET. This is the local calling area (rate center) where those prefixes were first assigned.
- Local phone company 20%
- Internet / business phone carrier 60%
- Phone company 20%
Every prefix in Baldwin
Search the first six digits of a number in this list. If it's here, the number started in Baldwin with the carrier shown. If it isn't, check the Michigan page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 231-338 | Bandwidth | Internet / business phone carrier | – |
| 231-368 | Interactive Services Network | Internet / business phone carrier | – |
| 231-440 | 123.NET | Phone company | 2002 |
| 231-449 | Charter / Spectrum | Internet / business phone carrier | 2021 |
| 231-745 | AT&T (local phone) | Local phone company | – |
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.