All assignees
798 prefixes in 312 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 312-500 | CHICGOZN01 | 224C | 2018-05-22 | Yes |
| 312-501 | LA GRANGE | 6333 | — | Yes |
| 312-502 | CHICGOZN01 | 6333 | — | — |
| 312-503 | CHICGOZN01 | 7136 | — | Yes |
| 312-504 | CHICGOZN01 | 6534 | — | — |
| 312-505 | CHICGOZN01 | 6333 | — | — |
| 312-506 | CHICGOZN01 | 460K | 2004-05-24 | Yes |
| 312-507 | CHICGOZN01 | 9329 | — | Yes |
| 312-508 | CHICGOZN01 | 063E | 2012-03-19 | Yes |
| 312-509 | CHICGOZN01 | 063E | 2012-03-06 | Yes |
| 312-510 | HINSDALE | 6534 | — | Yes |
| 312-511 | XXXXXXXXXX | MULT | — | — |
| 312-512 | CHICGOZN01 | 6630 | — | — |
| 312-513 | CHICGOZN01 | 6534 | — | — |
| 312-514 | CHICGOZN01 | 9748 | 2001-04-13 | — |
| 312-515 | CHICGOZN01 | 6333 | — | — |
| 312-516 | CHICGOZN01 | 9329 | — | — |
| 312-517 | CHICGOZN01 | 7229 | 2015-02-09 | Yes |
| 312-518 | WHEELING | 6534 | — | Yes |
| 312-519 | CHICGOZN01 | 6333 | — | — |
| 312-520 | CHICGOZN01 | 6333 | — | — |
| 312-521 | CHICGOZN01 | 7136 | — | Yes |
| 312-522 | CHICGOZN01 | 6529 | 2014-08-22 | Yes |
| 312-523 | CHICGOZN01 | 6529 | — | Yes |
| 312-524 | WHEELING | 6534 | — | Yes |
| 312-525 | CHICGOZN01 | 7229 | 2002-03-20 | Yes |
| 312-526 | CHICGOZN01 | 9329 | — | Yes |
| 312-527 | CHICGOZN01 | 9329 | — | — |
| 312-528 | CHICGOZN01 | 9329 | — | Yes |
| 312-529 | CHICGOZN01 | 7421 | — | Yes |
| 312-530 | CHICGOZN01 | 495J | 2020-07-28 | Yes |
| 312-531 | HINSDALE | 6534 | — | Yes |
| 312-532 | CHICGOZN01 | 6529 | — | Yes |
| 312-533 | CHICGOZN01 | 6333 | — | Yes |
| 312-534 | CHICGOZN01 | 9329 | 2008-09-17 | Yes |
| 312-535 | CHICGOZN01 | 984E | 2017-07-20 | Yes |
| 312-536 | CHICGOZN01 | 6529 | 2015-06-26 | Yes |
| 312-537 | CHICGOZN01 | 9329 | — | Yes |
| 312-538 | CHICGOZN01 | 5562 | 2017-07-21 | Yes |
| 312-539 | CHICGOZN01 | 6529 | 2016-01-11 | Yes |
| 312-540 | CHICGOZN01 | 9329 | — | — |
| 312-541 | CHICGOZN01 | 9329 | — | — |
| 312-542 | CHICGOZN01 | 9329 | — | — |
| 312-543 | CHICGOZN01 | 6534 | — | — |
| 312-544 | CHICGOZN01 | 9329 | — | Yes |
| 312-545 | CHICGOZN01 | 6529 | — | Yes |
| 312-546 | CHICGOZN01 | 6115 | — | Yes |
| 312-547 | CHICGOZN01 | 6534 | — | Yes |
| 312-548 | CHICGOZN01 | 6115 | 2007-09-05 | Yes |
| 312-549 | CHICGOZN01 | 7136 | 2015-09-25 | Yes |
| 312-550 | CHICGOZN01 | 6333 | — | — |
| 312-551 | CHICGOZN01 | 9329 | — | — |
| 312-552 | CHICGOZN01 | 9329 | — | — |
| 312-553 | CHICGOZN01 | 9329 | — | — |
| 312-554 | CHICGOZN01 | 9329 | — | Yes |
| 312-555 | DIR ASST | MULT | — | — |
| 312-556 | CHICGOZN01 | 9329 | — | — |
| 312-557 | CHICGOZN01 | 9329 | — | — |
| 312-558 | CHICGOZN01 | 9329 | — | — |
| 312-559 | CHICGOZN01 | 9329 | — | — |
| 312-560 | CHICGOZN01 | 6534 | — | — |
| 312-561 | CHICGOZN01 | 6333 | 2012-06-20 | Yes |
| 312-562 | CHICGOZN01 | 6630 | — | — |
| 312-563 | CHICGOZN01 | 9329 | — | — |
| 312-564 | CHICGOZN01 | 460K | 2006-11-13 | Yes |
| 312-565 | CHICGOZN01 | 9329 | — | — |
| 312-566 | CHICGOZN01 | 9329 | — | Yes |
| 312-567 | CHICGOZN01 | 9329 | — | — |
| 312-568 | CHICGOZN01 | 9329 | — | Yes |
| 312-569 | CHICGOZN01 | 9329 | — | Yes |
| 312-570 | CHICGOZN01 | 9329 | — | — |
| 312-571 | CHICGOZN01 | 6630 | — | — |
| 312-572 | CHICGOZN01 | 9329 | — | Yes |
| 312-573 | CHICGOZN01 | 9329 | — | — |
| 312-574 | CHICGOZN01 | 9329 | — | Yes |
| 312-575 | CHICGOZN01 | 9329 | — | — |
| 312-576 | CHICGOZN01 | 6534 | — | — |
| 312-577 | CHICGOZN01 | 7196 | — | — |
| 312-578 | CHICGOZN01 | 9329 | — | — |
| 312-579 | CHICGOZN01 | 6333 | 2017-07-25 | Yes |
| 312-580 | CHICGOZN01 | 9329 | — | — |
| 312-581 | CHICGOZN01 | 6534 | 2017-07-31 | Yes |
| 312-582 | CHICGOZN01 | 9329 | 2002-05-16 | Yes |
| 312-583 | CHICGOZN01 | 9329 | — | Yes |
| 312-584 | CHICGOZN01 | 597F | 2018-08-14 | Yes |
| 312-585 | CHICGOZN01 | 7229 | 2013-04-16 | Yes |
| 312-586 | CHICGOZN01 | 224C | 2016-05-04 | Yes |
| 312-587 | CHICGOZN01 | 9329 | — | — |
| 312-588 | CHICGOZN01 | 9329 | — | Yes |
| 312-589 | CHICGOZN01 | 9329 | — | Yes |
| 312-590 | CHICGOZN01 | 6333 | — | — |
| 312-591 | CHICGOZN01 | 9329 | — | — |
| 312-592 | CHICGOZN01 | 9329 | — | — |
| 312-593 | CHICGOZN01 | 6529 | — | — |
| 312-594 | CHICGOZN01 | 7229 | 2008-11-06 | Yes |
| 312-595 | CHICGOZN01 | 9329 | — | — |
| 312-596 | CHICGOZN01 | 7136 | — | — |
| 312-597 | CHICGOZN01 | 6333 | 2016-10-04 | Yes |
| 312-598 | CHICGOZN01 | 224C | 2019-01-24 | Yes |
| 312-599 | CHICGOZN01 | 6333 | 2016-11-21 | 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.