Phone numbers in Hillsdale, Michigan
Hillsdale has 15 phone prefixes in area code 517.
Biggest holders: Verizon Wireless, AT&T Mobility, AT&T (local phone). This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 53%
- Local phone company 20%
- Internet / business phone carrier 13%
- Phone company 13%
Every prefix in Hillsdale
Search the first six digits of a number in this list. If it's here, the number started in Hillsdale with the carrier shown. If it isn't, check the Michigan page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 517-212 | Verizon Wireless | Mobile carrier | 2004 |
| 517-297 | AT&T Mobility | Mobile carrier | 2021 |
| 517-320 | Verizon Wireless | Mobile carrier | – |
| 517-387 | AT&T Mobility | Mobile carrier | 2026 |
| 517-398 | AT&T Mobility | Mobile carrier | – |
| 517-425 | Verizon Wireless | Mobile carrier | – |
| 517-437 | AT&T (local phone) | Local phone company | – |
| 517-439 | AT&T (local phone) | Local phone company | – |
| 517-607 | AT&T (local phone) | Local phone company | – |
| 517-610 | T-Mobile (including Sprint) | Mobile carrier | 2002 |
| 517-689 | Interactive Services Network | Internet / business phone carrier | 2001 |
| 517-797 | Windstream (PAETEC) | Internet / business phone carrier | 2001 |
| 517-825 | Verizon Wireless | Mobile carrier | – |
| 517-828 | 123.NET | Phone company | 2002 |
| 517-964 | Acd Telecom | Phone company | 2001 |
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.