All assignees
239 prefixes in 331 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 331-300 | AURORA | 6529 | 2016-03-17 | Yes |
| 331-301 | AURORA | 5562 | — | Yes |
| 331-302 | AURORA | 6333 | 2013-02-11 | Yes |
| 331-303 | ELBURN | 984E | — | Yes |
| 331-304 | BARTLETT | 6529 | 2015-02-20 | Yes |
| 331-305 | NAPERVILLE | 6333 | 2013-08-15 | Yes |
| 331-306 | DOWNERSGRV | 224C | 2023-09-19 | Yes |
| 331-307 | LOMBARD | 6529 | 2014-10-13 | Yes |
| 331-308 | BARTLETT | 984E | 2014-12-23 | Yes |
| 331-309 | LEMONT | 939H | — | Yes |
| 331-310 | BIG ROCK | 984E | 2014-12-29 | Yes |
| 331-311 | MULT | — | — | |
| 331-312 | AURORA | 6333 | 2023-11-06 | Yes |
| 331-313 | NAPERVILLE | 624H | 2022-08-16 | Yes |
| 331-314 | ST CHARLES | 6333 | 2023-11-17 | Yes |
| 331-315 | LOMBARD | 6534 | 2016-08-08 | Yes |
| 331-316 | NAPERVILLE | 939H | 2024-01-04 | Yes |
| 331-317 | HINSDALE | 939H | 2024-01-05 | Yes |
| 331-318 | LEMONT | 984E | — | Yes |
| 331-319 | AURORA | 224C | 2024-01-24 | Yes |
| 331-320 | BARTLETT | 224C | 2024-01-30 | Yes |
| 331-321 | AURORA | 6529 | 2015-07-20 | Yes |
| 331-322 | LOMBARD | 224C | 2024-02-08 | Yes |
| 331-323 | GLEN ELLYN | 224C | 2024-02-08 | Yes |
| 331-324 | YORKVILLE | 224C | 2024-03-13 | Yes |
| 331-325 | LEMONT | 624H | 2024-03-21 | Yes |
| 331-326 | DOWNERSGRV | 224C | 2024-03-28 | Yes |
| 331-327 | ST CHARLES | 6333 | 2024-11-14 | Yes |
| 331-328 | NAPERVILLE | 6534 | 2024-12-16 | Yes |
| 331-329 | AURORA | 224C | 2025-01-08 | Yes |
| 331-330 | NAPERVILLE | 6534 | 2008-08-19 | Yes |
| 331-331 | AURORA | 224C | 2025-08-21 | Yes |
| 331-332 | NAPERVILLE | 6534 | 2008-11-03 | Yes |
| 331-333 | NAPERVILLE | 6534 | 2008-11-03 | Yes |
| 331-334 | BATAVIA | 224C | 2021-06-02 | Yes |
| 331-335 | ST CHARLES | 6534 | 2024-04-30 | Yes |
| 331-336 | AURORA | 965H | 2019-10-11 | Yes |
| 331-337 | OSWEGO | 6534 | 2025-01-09 | Yes |
| 331-338 | AURORA | 624H | 2025-01-29 | Yes |
| 331-339 | AURORA | 6333 | 2025-08-28 | Yes |
| 331-340 | ITASCA | 224C | 2025-11-05 | Yes |
| 331-341 | PLANO | 224C | 2021-03-30 | Yes |
| 331-342 | NAPERVILLE | 6333 | 2025-11-18 | Yes |
| 331-343 | DOWNERSGRV | 224C | 2023-01-13 | Yes |
| 331-344 | W CHICAGO | 224C | 2026-02-02 | Yes |
| 331-345 | NAPERVILLE | 965H | 2020-11-18 | Yes |
| 331-346 | NAPERVILLE | 6333 | 2026-05-18 | Yes |
| 331-347 | WHEATON | 224C | 2026-07-28 | Yes |
| 331-348 | ELBURN | 965H | 2019-10-11 | Yes |
| 331-349 | ST CHARLES | 6534 | 2026-08-14 | Yes |
| 331-356 | BARTLETT | 965H | 2019-10-10 | Yes |
| 331-373 | OSWEGO | 516J | 2022-02-25 | Yes |
| 331-385 | AURORA | 6534 | 2016-09-28 | Yes |
| 331-388 | SUGARGROVE | 965H | 2021-01-25 | Yes |
| 331-399 | DOWNERSGRV | 965H | 2021-01-22 | Yes |
| 331-400 | OSWEGO | 965H | 2019-08-08 | Yes |
| 331-401 | NAPERVILLE | 6115 | 2015-12-14 | Yes |
| 331-411 | MULT | — | — | |
| 331-422 | ST CHARLES | 6115 | 2008-11-13 | Yes |
| 331-425 | AURORA | 6529 | 2007-07-11 | Yes |
| 331-426 | LEMONT | 516J | 2022-02-18 | Yes |
| 331-431 | AURORA | 984E | 2010-05-26 | Yes |
| 331-442 | ST CHARLES | 6333 | 2008-10-30 | Yes |
| 331-444 | NAPERVILLE | 6333 | 2010-08-04 | Yes |
| 331-452 | AURORA | 6333 | 2007-09-20 | Yes |
| 331-454 | AURORA | 6534 | 2009-05-07 | Yes |
| 331-456 | ROSELLE | 460K | 2007-12-05 | Yes |
| 331-457 | NAPERVILLE | 6333 | 2008-11-14 | Yes |
| 331-462 | LOMBARD | 7196 | 2008-08-23 | Yes |
| 331-465 | W CHICAGO | 6534 | 2007-10-17 | Yes |
| 331-466 | GLEN ELLYN | 516J | 2022-02-17 | Yes |
| 331-472 | NAPERVILLE | 6529 | 2008-10-22 | Yes |
| 331-481 | DOWNERSGRV | 6333 | 2008-10-29 | Yes |
| 331-500 | GENEVA | 965H | 2021-01-04 | Yes |
| 331-511 | MULT | — | — | |
| 331-529 | NAPERVILLE | 965H | 2019-08-08 | Yes |
| 331-551 | LOMBARD | 6534 | 2008-11-05 | Yes |
| 331-555 | MULT | — | — | |
| 331-575 | AURORA | 6529 | 2007-09-18 | Yes |
| 331-588 | ST CHARLES | 6534 | 2010-02-15 | Yes |
| 331-591 | — | — | ||
| 331-600 | WHEATON | 965H | 2019-08-08 | Yes |
| 331-611 | MULT | — | — | |
| 331-625 | DOWNERSGRV | 6333 | 2009-10-16 | Yes |
| 331-627 | LOMBARD | 516J | 2022-02-25 | Yes |
| 331-631 | DOWNERSGRV | 624H | 2022-07-07 | Yes |
| 331-642 | ELMHURST | 984E | — | Yes |
| 331-643 | AURORA | 6529 | 2007-09-18 | Yes |
| 331-645 | ELMHURST | 6529 | 2007-11-05 | Yes |
| 331-666 | AURORA | 224C | 2017-09-29 | Yes |
| 331-684 | AURORA | 8702 | 2007-07-12 | Yes |
| 331-688 | NAPERVILLE | 516J | 2022-02-17 | Yes |
| 331-700 | — | — | ||
| 331-701 | NAPERVILLE | 6333 | 2014-12-11 | Yes |
| 331-702 | NAPERVILLE | 7196 | 2013-10-23 | Yes |
| 331-703 | W CHICAGO | 6529 | 2013-10-24 | Yes |
| 331-704 | KANEVILLE | 984E | 2015-04-21 | Yes |
| 331-707 | AURORA | 6529 | 2016-08-23 | Yes |
| 331-711 | MULT | — | — | |
| 331-716 | WHEATON | 224C | 2016-01-18 | Yes |
These are initial assignees from NANPA CO-code records — because of number portability, the current serving carrier of individual numbers may differ. Bulk export requires a membership.