Phone numbers in Ottawa, Illinois
Ottawa has 11 phone prefixes in area code 815.
Biggest holders: Level 3 (Lumen), AT&T (local phone), Teleport Communications America. This is the local calling area (rate center) where those prefixes were first assigned.
- Local phone company 27%
- Internet / business phone carrier 55%
- Phone company 18%
Every prefix in Ottawa
Search the first six digits of a number in this list. If it's here, the number started in Ottawa with the carrier shown. If it isn't, check the Illinois page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 815-313 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 815-324 | Mcc Telephony | Internet / business phone carrier | 2010 |
| 815-366 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 815-431 | AT&T (local phone) | Local phone company | – |
| 815-433 | AT&T (local phone) | Local phone company | – |
| 815-434 | AT&T (local phone) | Local phone company | – |
| 815-587 | Level 3 (Lumen) | Internet / business phone carrier | 2002 |
| 815-606 | First Communications | Phone company | – |
| 815-617 | Teleport Communications America | Internet / business phone carrier | – |
| 815-640 | Teleport Communications America | Internet / business phone carrier | 2001 |
| 815-665 | Rcn Telecom Services Of Illinios | 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.