ILLINOIS BELL TEL CO
334 prefixes in 312 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 312-447 | CHICGOZN01 | 9329 | — | Yes |
| 312-454 | CHICGOZN01 | 9329 | — | — |
| 312-455 | CHICGOZN01 | 9329 | — | — |
| 312-456 | CHICGOZN01 | 9329 | — | — |
| 312-458 | CHICGOZN01 | 9329 | — | Yes |
| 312-460 | CHICGOZN01 | 9329 | — | Yes |
| 312-461 | CHICGOZN01 | 9329 | — | — |
| 312-462 | CHICGOZN01 | 9329 | — | Yes |
| 312-463 | CHICGOZN01 | 9329 | — | Yes |
| 312-464 | CHICGOZN01 | 9329 | — | — |
| 312-466 | CHICGOZN01 | 9329 | — | — |
| 312-467 | CHICGOZN01 | 9329 | — | — |
| 312-469 | CHICGOZN01 | 9329 | — | Yes |
| 312-472 | CHICGOZN01 | 9329 | 2005-10-27 | Yes |
| 312-474 | CHICGOZN01 | 9329 | — | — |
| 312-475 | CHICGOZN01 | 9329 | — | — |
| 312-482 | CHICGOZN01 | 9329 | — | — |
| 312-491 | CHICGOZN01 | 9329 | — | — |
| 312-492 | CHICGOZN01 | 9329 | — | Yes |
| 312-494 | CHICGOZN01 | 9329 | — | — |
| 312-496 | CHICGOZN01 | 9329 | — | Yes |
| 312-499 | CHICGOZN01 | 9329 | — | — |
| 312-507 | CHICGOZN01 | 9329 | — | Yes |
| 312-516 | CHICGOZN01 | 9329 | — | — |
| 312-526 | CHICGOZN01 | 9329 | — | Yes |
| 312-527 | CHICGOZN01 | 9329 | — | — |
| 312-528 | CHICGOZN01 | 9329 | — | Yes |
| 312-534 | CHICGOZN01 | 9329 | 2008-09-17 | Yes |
| 312-537 | CHICGOZN01 | 9329 | — | Yes |
| 312-540 | CHICGOZN01 | 9329 | — | — |
| 312-541 | CHICGOZN01 | 9329 | — | — |
| 312-542 | CHICGOZN01 | 9329 | — | — |
| 312-544 | CHICGOZN01 | 9329 | — | Yes |
| 312-551 | CHICGOZN01 | 9329 | — | — |
| 312-552 | CHICGOZN01 | 9329 | — | — |
| 312-553 | CHICGOZN01 | 9329 | — | — |
| 312-554 | CHICGOZN01 | 9329 | — | Yes |
| 312-556 | CHICGOZN01 | 9329 | — | — |
| 312-557 | CHICGOZN01 | 9329 | — | — |
| 312-558 | CHICGOZN01 | 9329 | — | — |
| 312-559 | CHICGOZN01 | 9329 | — | — |
| 312-563 | CHICGOZN01 | 9329 | — | — |
| 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 | — | — |
| 312-572 | CHICGOZN01 | 9329 | — | Yes |
| 312-573 | CHICGOZN01 | 9329 | — | — |
| 312-574 | CHICGOZN01 | 9329 | — | Yes |
| 312-575 | CHICGOZN01 | 9329 | — | — |
| 312-578 | CHICGOZN01 | 9329 | — | — |
| 312-580 | CHICGOZN01 | 9329 | — | — |
| 312-582 | CHICGOZN01 | 9329 | 2002-05-16 | Yes |
| 312-583 | CHICGOZN01 | 9329 | — | Yes |
| 312-587 | CHICGOZN01 | 9329 | — | — |
| 312-588 | CHICGOZN01 | 9329 | — | Yes |
| 312-589 | CHICGOZN01 | 9329 | — | Yes |
| 312-591 | CHICGOZN01 | 9329 | — | — |
| 312-592 | CHICGOZN01 | 9329 | — | — |
| 312-595 | CHICGOZN01 | 9329 | — | — |
| 312-603 | CHICGOZN01 | 9329 | — | — |
| 312-606 | CHICGOZN01 | 9329 | — | — |
| 312-609 | CHICGOZN01 | 9329 | — | Yes |
| 312-612 | CHICGOZN01 | 9329 | — | Yes |
| 312-614 | CHICGOZN01 | 9329 | 2012-10-19 | Yes |
| 312-616 | CHICGOZN01 | 9329 | — | — |
| 312-621 | CHICGOZN01 | 9329 | — | — |
| 312-627 | CHICGOZN01 | 9329 | — | Yes |
| 312-629 | CHICGOZN01 | 9329 | — | — |
| 312-630 | CHICGOZN01 | 9329 | — | — |
| 312-632 | CHICGOZN01 | 9329 | — | Yes |
| 312-633 | CHICGOZN01 | 9329 | — | — |
| 312-634 | CHICGOZN01 | 9329 | — | — |
| 312-640 | CHICGOZN01 | 9329 | — | — |
| 312-641 | CHICGOZN01 | 9329 | — | — |
| 312-642 | CHICGOZN01 | 9329 | — | — |
| 312-644 | CHICGOZN01 | 9329 | — | — |
| 312-645 | CHICGOZN01 | 9329 | — | — |
| 312-648 | CHICGOZN01 | 9329 | — | Yes |
| 312-649 | CHICGOZN01 | 9329 | — | — |
| 312-651 | CHICGOZN01 | 9329 | — | Yes |
| 312-652 | CHICGOZN01 | 9329 | — | — |
| 312-653 | CHICGOZN01 | 9329 | — | — |
| 312-654 | CHICGOZN01 | 9329 | — | — |
| 312-655 | CHICGOZN01 | 9329 | — | — |
| 312-658 | CHICGOZN01 | 9329 | — | — |
| 312-661 | CHICGOZN01 | 9329 | — | Yes |
| 312-662 | CHICGOZN01 | 9329 | — | Yes |
| 312-663 | CHICGOZN01 | 9329 | — | — |
| 312-664 | CHICGOZN01 | 9329 | — | — |
| 312-666 | CHICGOZN01 | 9329 | — | — |
| 312-669 | CHICGOZN01 | 9329 | — | Yes |
| 312-670 | CHICGOZN01 | 9329 | — | — |
| 312-672 | CHICGOZN01 | 9329 | — | Yes |
| 312-674 | CHICGOZN01 | 9329 | — | Yes |
| 312-675 | CHICGOZN01 | 9329 | — | Yes |
| 312-681 | CHICGOZN01 | 9329 | — | Yes |
| 312-683 | CHICGOZN01 | 9329 | — | 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.