All assignees
239 prefixes in 331 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 331-200 | BARTLETT | 6529 | 2011-07-11 | Yes |
| 331-201 | DOWNERSGRV | 6333 | 2012-01-06 | Yes |
| 331-202 | ELMHURST | 6529 | 2012-01-17 | Yes |
| 331-203 | AURORA | 6529 | 2011-10-12 | Yes |
| 331-204 | NAPERVILLE | 224C | 2015-12-10 | Yes |
| 331-205 | AURORA | 6529 | 2011-10-21 | Yes |
| 331-206 | AURORA | 6529 | 2011-10-12 | Yes |
| 331-207 | YORKVILLE | 6115 | 2011-11-01 | Yes |
| 331-208 | AURORA | 6115 | 2011-11-08 | Yes |
| 331-209 | ELMHURST | 6115 | 2012-01-17 | Yes |
| 331-210 | ST CHARLES | 063E | 2012-03-06 | Yes |
| 331-211 | MULT | — | — | |
| 331-212 | AURORA | 7196 | 2012-04-05 | Yes |
| 331-213 | NAPERVILLE | 6333 | 2011-09-06 | Yes |
| 331-214 | DOWNERSGRV | 6333 | 2012-06-20 | Yes |
| 331-215 | NAPERVILLE | 6333 | 2012-09-28 | Yes |
| 331-216 | OSWEGO | 6534 | 2012-10-31 | Yes |
| 331-217 | LOMBARD | 224C | 2023-07-11 | Yes |
| 331-218 | WHEATON | 6529 | 2013-07-09 | Yes |
| 331-219 | AURORA | 073H | 2017-03-16 | Yes |
| 331-220 | AURORA | 6529 | 2011-07-12 | Yes |
| 331-221 | ELMHURST | 9329 | 2009-01-21 | Yes |
| 331-222 | ST CHARLES | 6534 | 2008-10-28 | Yes |
| 331-223 | ST CHARLES | 6534 | 2008-10-28 | Yes |
| 331-224 | ITASCA | 224C | 2023-06-05 | Yes |
| 331-225 | ELMHURST | 6529 | 2011-08-22 | Yes |
| 331-226 | NAPERVILLE | 6529 | 2017-03-20 | Yes |
| 331-227 | SUGARGROVE | 6333 | 2016-05-17 | Yes |
| 331-228 | ST CHARLES | 829J | 2011-09-21 | Yes |
| 331-229 | NAPERVILLE | 6333 | 2012-11-27 | Yes |
| 331-230 | AURORA | 6529 | 2017-04-05 | Yes |
| 331-231 | NAPERVILLE | 6534 | 2017-08-07 | Yes |
| 331-232 | W CHICAGO | 6534 | 2017-08-08 | Yes |
| 331-233 | DOWNERSGRV | 073H | 2017-03-13 | Yes |
| 331-234 | SUGARGROVE | 6333 | 2013-07-08 | Yes |
| 331-235 | ST CHARLES | 6534 | 2017-10-17 | Yes |
| 331-236 | WHEATON | 6529 | 2017-04-05 | Yes |
| 331-237 | NAPERVILLE | 7196 | 2017-11-07 | Yes |
| 331-238 | DOWNERSGRV | 7136 | 2017-12-19 | Yes |
| 331-239 | YORKVILLE | 224C | 2018-08-27 | Yes |
| 331-240 | W CHICAGO | 063E | 2013-04-10 | Yes |
| 331-241 | LOMBARD | 224C | — | Yes |
| 331-242 | LOMBARD | 6529 | 2018-10-19 | Yes |
| 331-243 | LOMBARD | 6529 | 2018-10-19 | Yes |
| 331-244 | NAPERVILLE | 224C | 2017-09-21 | Yes |
| 331-245 | BARTLETT | 6529 | 2013-04-18 | Yes |
| 331-246 | LEMONT | 6529 | 2018-10-19 | Yes |
| 331-247 | NAPERVILLE | 197D | 2018-11-21 | Yes |
| 331-248 | GENEVA | 318J | 2007-07-06 | Yes |
| 331-249 | NAPERVILLE | 224C | 2018-12-05 | Yes |
| 331-250 | AURORA | 6529 | 2012-04-10 | Yes |
| 331-251 | DOWNERSGRV | 6333 | 2012-12-05 | Yes |
| 331-252 | WARRENVL | 7136 | 2016-06-02 | Yes |
| 331-253 | LEMONT | 6529 | 2014-10-27 | Yes |
| 331-254 | SUGARGROVE | 6529 | 2014-07-16 | Yes |
| 331-255 | AURORA | 224C | 2017-08-22 | Yes |
| 331-256 | AURORA | 6333 | 2011-09-13 | Yes |
| 331-257 | AURORA | 6534 | 2020-01-17 | Yes |
| 331-258 | AURORA | 224C | — | Yes |
| 331-259 | SUGARGROVE | 063E | — | Yes |
| 331-260 | DOWNERSGRV | 7136 | 2019-02-25 | Yes |
| 331-261 | LEMONT | 6529 | 2019-06-20 | Yes |
| 331-262 | AURORA | 6529 | 2008-07-30 | Yes |
| 331-263 | ITASCA | 224C | 2016-03-11 | Yes |
| 331-264 | HINSDALE | 6115 | 2020-03-06 | Yes |
| 331-265 | GENEVA | 224C | — | Yes |
| 331-266 | ST CHARLES | 6534 | 2020-04-10 | Yes |
| 331-267 | LOMBARD | 197D | 2020-09-18 | Yes |
| 331-268 | SUGARGROVE | 6529 | 2021-01-14 | Yes |
| 331-269 | AURORA | 6529 | 2021-05-14 | Yes |
| 331-270 | AURORA | 224C | 2021-07-20 | Yes |
| 331-271 | HINSDALE | 224C | 2020-10-21 | Yes |
| 331-272 | ST CHARLES | 224C | 2021-07-15 | Yes |
| 331-273 | LEMONT | 224C | 2021-06-09 | Yes |
| 331-274 | AURORA | 6529 | 2021-08-03 | Yes |
| 331-275 | BARTLETT | 6529 | 2021-08-03 | Yes |
| 331-276 | ST CHARLES | 6333 | 2014-11-10 | Yes |
| 331-277 | LOMBARD | 6534 | 2021-08-06 | Yes |
| 331-278 | AURORA | 6534 | 2021-08-13 | Yes |
| 331-279 | ELMHURST | 829J | 2021-10-15 | Yes |
| 331-280 | DOWNERSGRV | 6333 | 2021-12-29 | Yes |
| 331-281 | NAPERVILLE | 9329 | 2012-10-25 | Yes |
| 331-282 | HINSDALE | 224C | 2021-12-10 | Yes |
| 331-283 | GENEVA | 6529 | 2022-02-23 | Yes |
| 331-284 | BARTLETT | 6529 | 2022-03-11 | Yes |
| 331-285 | NAPERVILLE | 6333 | 2022-05-04 | Yes |
| 331-286 | ST CHARLES | 6333 | 2022-07-15 | Yes |
| 331-287 | AURORA | 984E | 2022-07-20 | Yes |
| 331-288 | ELBURN | 516J | 2022-02-17 | Yes |
| 331-289 | HINSDALE | 6529 | 2022-08-12 | Yes |
| 331-290 | AURORA | 6333 | 2022-08-26 | Yes |
| 331-291 | DOWNERSGRV | 6333 | 2022-08-26 | Yes |
| 331-292 | DOWNERSGRV | 624H | 2022-10-14 | Yes |
| 331-293 | AURORA | 6534 | 2023-01-10 | Yes |
| 331-294 | NAPERVILLE | 6333 | 2023-01-12 | Yes |
| 331-295 | AURORA | 732J | 2023-02-07 | Yes |
| 331-296 | WHEATON | 490J | 2023-04-18 | Yes |
| 331-297 | BATAVIA | 224C | 2023-08-09 | Yes |
| 331-298 | NAPERVILLE | 224C | 2023-08-09 | Yes |
| 331-299 | HINSDALE | 965H | 2021-01-04 | 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.