Phone numbers in DeKalb, Illinois
DeKalb has 39 phone prefixes in area codes 779, 815.
Biggest holders: Frontier, Verizon Wireless, T-Mobile (including Sprint). This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 41%
- Local phone company 18%
- Internet / business phone carrier 31%
- Phone company 10%
Every prefix in DeKalb
Search the first six digits of a number in this list. If it's here, the number started in DeKalb with the carrier shown. If it isn't, check the Illinois page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 779-212 | Nuso | Internet / business phone carrier | 2013 |
| 779-217 | Boost / Virgin Mobile | Mobile carrier | 2023 |
| 779-255 | Onvoy | Internet / business phone carrier | – |
| 779-270 | MCImetro (Verizon Business) | Internet / business phone carrier | 2020 |
| 779-276 | Stratus Networks | Phone company | 2020 |
| 779-334 | Level 3 (Lumen) | Internet / business phone carrier | 2020 |
| 779-365 | Nuso | Internet / business phone carrier | 2023 |
| 779-400 | Ymax Communications | Phone company | 2011 |
| 779-422 | Verizon Wireless | Mobile carrier | 2025 |
| 779-431 | T-Mobile (including Sprint) | Mobile carrier | 2025 |
| 779-446 | AT&T Enterprises | Phone company | 2026 |
| 779-775 | Skyetel | Internet / business phone carrier | 2021 |
| 779-777 | AT&T Mobility | Mobile carrier | 2008 |
| 779-902 | Onvoy | Internet / business phone carrier | 2021 |
| 779-910 | Onvoy | Internet / business phone carrier | 2021 |
| 815-217 | Digital Network Access Communications | Phone company | – |
| 815-375 | UScellular | Mobile carrier | – |
| 815-501 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 815-508 | AT&T Mobility | Mobile carrier | 2004 |
| 815-517 | MCImetro (Verizon Business) | Internet / business phone carrier | 2004 |
| 815-593 | T-Mobile (including Sprint) | Mobile carrier | – |
| 815-748 | Frontier | Local phone company | – |
| 815-751 | Verizon Wireless | Mobile carrier | – |
| 815-752 | Frontier | Local phone company | – |
| 815-753 | Frontier | Local phone company | – |
| 815-754 | Frontier | Local phone company | – |
| 815-756 | Frontier | Local phone company | – |
| 815-757 | UScellular | Mobile carrier | – |
| 815-758 | Frontier | Local phone company | – |
| 815-761 | Verizon Wireless | Mobile carrier | – |
| 815-762 | Verizon Wireless | Mobile carrier | – |
| 815-764 | UScellular | Mobile carrier | – |
| 815-766 | UScellular | Mobile carrier | – |
| 815-787 | Frontier | Local phone company | – |
| 815-793 | T-Mobile (including Sprint) | Mobile carrier | 2001 |
| 815-901 | Comcast | Internet / business phone carrier | 2005 |
| 815-909 | T-Mobile (including Sprint) | Mobile carrier | 2001 |
| 815-981 | Level 3 (Lumen) | Internet / business phone carrier | 2002 |
| 815-995 | Teleport Communications America | Internet / business phone carrier | 2009 |
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.