Phone numbers in Oswego, Illinois
Oswego has 13 phone prefixes in area codes 331, 630.
Biggest holders: AT&T Mobility, AT&T (local phone), First Communications. This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 31%
- Local phone company 15%
- Internet / business phone carrier 38%
- Phone company 15%
Every prefix in Oswego
Search the first six digits of a number in this list. If it's here, the number started in Oswego with the carrier shown. If it isn't, check the Illinois page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 331-216 | AT&T Mobility | Mobile carrier | 2012 |
| 331-337 | AT&T Mobility | Mobile carrier | 2025 |
| 331-373 | TON80 Communications | Internet / business phone carrier | 2022 |
| 331-400 | Fractel | Internet / business phone carrier | 2019 |
| 331-717 | AT&T Mobility | Mobile carrier | 2016 |
| 331-725 | AT&T Mobility | Mobile carrier | – |
| 331-999 | Bandwidth | Internet / business phone carrier | 2010 |
| 630-383 | MCImetro (Verizon Business) | Internet / business phone carrier | – |
| 630-551 | AT&T (local phone) | Local phone company | – |
| 630-554 | AT&T (local phone) | Local phone company | – |
| 630-608 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 630-630 | First Communications | Phone company | 2007 |
| 630-636 | First Communications | 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.