Phone numbers in Summum, Illinois
Summum has 3 phone prefixes in area code 309.
Biggest holders: AT&T Mobility, Mid Century Tel. Coop. This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 67%
- Phone company 33%
Every prefix in Summum
Search the first six digits of a number in this list. If it's here, the number started in Summum with the carrier shown. If it isn't, check the Illinois page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 309-500 | AT&T Mobility | Mobile carrier | 2021 |
| 309-759 | Mid Century Tel. Coop | Phone company | – |
| 309-991 | AT&T Mobility | Mobile carrier | 2026 |
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.