Phone numbers in Custer, South Dakota
Custer has 3 phone prefixes in area code 605.
Biggest holders: AT&T Mobility, Verizon Wireless, Golden West Telecommunications. This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 67%
- Local phone company 33%
Every prefix in Custer
Search the first six digits of a number in this list. If it's here, the number started in Custer with the carrier shown. If it isn't, check the South Dakota page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 605-440 | AT&T Mobility | Mobile carrier | 2001 |
| 605-517 | Verizon Wireless | Mobile carrier | 2003 |
| 605-673 | Golden West Telecommunications | 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.