All assignees
800 prefixes in 303 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 303-500 | HUDSON | 6118 | 2005-01-04 | Yes |
| 303-501 | DENVER | 6567 | 2006-01-26 | Yes |
| 303-502 | FORTLUPTON | 6567 | 2005-12-13 | Yes |
| 303-503 | DENVER | 6567 | — | — |
| 303-504 | DENVER | 9636 | — | — |
| 303-505 | DENVER | 6529 | 2012-11-09 | Yes |
| 303-506 | FORTLUPTON | 6010 | 2001-09-13 | Yes |
| 303-507 | DENVER | 6529 | — | Yes |
| 303-508 | DENVER | 9748 | — | — |
| 303-509 | DENVER | 9748 | — | — |
| 303-510 | DENVER | 9748 | — | — |
| 303-511 | XXXXXXXXXX | MULT | — | — |
| 303-512 | DENVER | 9636 | — | Yes |
| 303-513 | DENVER | 6010 | 2002-02-15 | — |
| 303-514 | DENVER | 6567 | — | — |
| 303-515 | DENVER | 026D | 2011-11-14 | Yes |
| 303-516 | DENVER | 9636 | — | — |
| 303-517 | DENVER | 6010 | — | — |
| 303-518 | DENVER | 6567 | — | — |
| 303-519 | DENVER | 6567 | — | Yes |
| 303-520 | DENVER | 6529 | — | Yes |
| 303-521 | DENVER | 6529 | — | Yes |
| 303-522 | DENVER | 6529 | — | Yes |
| 303-523 | DENVER | 6529 | — | — |
| 303-524 | DENVER | 7378 | — | Yes |
| 303-525 | DENVER | 6529 | — | Yes |
| 303-526 | DENVER | 9636 | — | Yes |
| 303-527 | DENVER | 9636 | — | — |
| 303-528 | DENVER | 9748 | — | — |
| 303-529 | DENVER | 026D | 2019-10-07 | Yes |
| 303-530 | DENVER | 9636 | — | — |
| 303-531 | DENVER | 7229 | — | Yes |
| 303-532 | LONGMONT | 829J | — | Yes |
| 303-533 | DENVER | 9636 | — | — |
| 303-534 | DENVER | 9636 | — | — |
| 303-535 | FORTLUPTON | 026D | — | Yes |
| 303-536 | HUDSON | 9636 | — | Yes |
| 303-537 | DENVER | 7378 | — | Yes |
| 303-538 | DENVER | 9636 | — | — |
| 303-539 | DENVER | 7229 | — | — |
| 303-540 | DENVER | 6630 | — | — |
| 303-541 | DENVER | 9636 | — | — |
| 303-542 | DENVER | 7229 | — | — |
| 303-543 | DENVER | 9636 | — | — |
| 303-544 | DENVER | 9636 | — | — |
| 303-545 | DENVER | 9636 | — | — |
| 303-546 | DENVER | 9636 | — | — |
| 303-547 | DENVER | 6118 | — | Yes |
| 303-548 | DENVER | 6567 | — | — |
| 303-549 | DENVER | 6567 | — | — |
| 303-550 | DENVER | 6567 | — | — |
| 303-551 | DENVER | 7229 | — | Yes |
| 303-552 | DENVER | 6118 | — | Yes |
| 303-553 | DENVER | 6630 | — | — |
| 303-554 | DENVER | 9636 | — | — |
| 303-555 | DIR ASST | MULT | — | — |
| 303-556 | DENVER | 9636 | — | — |
| 303-557 | DENVER | 6118 | — | Yes |
| 303-558 | DENVER | 6118 | — | Yes |
| 303-559 | DENVER | 9748 | — | — |
| 303-560 | DENVER | 6630 | — | — |
| 303-561 | DENVER | 9636 | — | — |
| 303-562 | DENVER | 6118 | — | Yes |
| 303-563 | DENVER | 6118 | — | Yes |
| 303-564 | DENVER | 6529 | — | — |
| 303-565 | DENVER | 026D | — | Yes |
| 303-566 | DENVER | 7229 | — | Yes |
| 303-567 | DENVER | 9636 | — | Yes |
| 303-568 | DENVER | 7378 | — | Yes |
| 303-569 | GEORGETOWN | 9636 | — | Yes |
| 303-570 | DENVER | 6010 | — | — |
| 303-571 | DENVER | 9636 | — | — |
| 303-572 | DENVER | 9636 | — | — |
| 303-573 | DENVER | 9636 | — | — |
| 303-574 | DENVER | 9636 | — | — |
| 303-575 | DENVER | 9636 | — | — |
| 303-576 | DENVER | 9636 | — | — |
| 303-577 | DENVER | 3467 | — | — |
| 303-578 | KEENESBURG | 6118 | 2006-09-12 | Yes |
| 303-579 | DENVER | 6567 | — | — |
| 303-580 | DENVER | 9748 | — | — |
| 303-581 | DENVER | 9636 | — | — |
| 303-582 | DENVER | 9636 | — | Yes |
| 303-583 | DENVER | 7378 | — | — |
| 303-584 | DENVER | 9636 | — | — |
| 303-585 | DENVER | 9636 | — | Yes |
| 303-586 | DENVER | 6118 | — | Yes |
| 303-587 | DENVER | 6529 | — | Yes |
| 303-588 | DENVER | 6010 | — | — |
| 303-589 | DENVER | 6010 | — | — |
| 303-590 | DENVER | 6118 | — | Yes |
| 303-591 | DENVER | 6529 | — | Yes |
| 303-592 | DENVER | 9636 | — | — |
| 303-593 | DENVER | 7378 | — | Yes |
| 303-594 | DENVER | 6567 | — | — |
| 303-595 | DENVER | 9636 | — | — |
| 303-596 | DENVER | 6529 | — | Yes |
| 303-597 | DENVER | 3467 | — | Yes |
| 303-598 | DENVER | 6529 | — | Yes |
| 303-599 | DENVER | 6630 | — | — |
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.