All assignees
239 prefixes in 331 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 331-717 | OSWEGO | 6534 | 2016-01-18 | Yes |
| 331-725 | OSWEGO | 6534 | — | Yes |
| 331-732 | GENEVA | 965H | 2019-10-11 | Yes |
| 331-746 | KANEVILLE | 516J | 2022-02-17 | Yes |
| 331-757 | LEMONT | 6529 | 2016-07-13 | Yes |
| 331-758 | AURORA | 965H | 2021-10-27 | Yes |
| 331-771 | ST CHARLES | 224C | 2016-02-10 | Yes |
| 331-775 | DOWNERSGRV | 318J | 2016-01-04 | Yes |
| 331-777 | DOWNERSGRV | 6333 | 2010-09-22 | Yes |
| 331-788 | GENEVA | 965H | 2021-01-25 | Yes |
| 331-800 | W CHICAGO | 224C | 2017-09-29 | Yes |
| 331-801 | DOWNERSGRV | 7136 | 2014-05-15 | Yes |
| 331-803 | LEMONT | 063E | 2013-04-10 | Yes |
| 331-806 | WHEATON | 318J | 2015-06-11 | Yes |
| 331-808 | PLANO | 984E | 2015-06-05 | Yes |
| 331-811 | MULT | — | — | |
| 331-814 | NAPERVILLE | 6529 | 2015-06-25 | Yes |
| 331-825 | GENEVA | 972C | — | — |
| 331-826 | ELMHURST | 6529 | 2008-11-18 | Yes |
| 331-837 | W CHICAGO | 516J | 2022-01-07 | Yes |
| 331-850 | BIG ROCK | 224C | 2021-03-30 | Yes |
| 331-866 | WHEATON | 516J | 2022-01-13 | Yes |
| 331-867 | YORKVILLE | 965H | 2020-07-14 | Yes |
| 331-871 | W CHICAGO | 224C | 2016-02-17 | Yes |
| 331-888 | WARRENVL | 063E | 2010-09-24 | Yes |
| 331-899 | LOMBARD | 965H | 2020-12-22 | Yes |
| 331-900 | ELMHURST | 965H | 2019-08-08 | Yes |
| 331-901 | ST CHARLES | 984E | 2015-04-23 | Yes |
| 331-903 | DOWNERSGRV | 516C | 2014-05-15 | Yes |
| 331-911 | MULT | — | — | |
| 331-946 | GLEN ELLYN | 965H | 2020-07-14 | Yes |
| 331-950 | — | — | ||
| 331-958 | — | — | ||
| 331-959 | — | — | ||
| 331-976 | — | — | ||
| 331-979 | ELMHURST | 318J | 2015-03-03 | Yes |
| 331-980 | AURORA | 6529 | 2014-10-13 | Yes |
| 331-998 | DOWNERSGRV | 6333 | 2015-09-16 | Yes |
| 331-999 | OSWEGO | 984E | 2010-09-22 | 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.