All assignees
768 prefixes in 406 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 406-400 | HAVRE | 958H | 2017-04-27 | Yes |
| 406-401 | GREATFALLS | 425J | 2019-05-29 | Yes |
| 406-402 | GREATFALLS | 6529 | 2017-08-04 | Yes |
| 406-403 | GREATFALLS | 453F | 2006-03-08 | Yes |
| 406-404 | BOZEMAN | 792K | 2012-04-03 | Yes |
| 406-405 | LIBBY | 453F | 2022-09-08 | Yes |
| 406-406 | MISSOULA | 509K | 2024-12-09 | Yes |
| 406-407 | KALISPELL | 6564 | 2010-08-16 | Yes |
| 406-408 | HAYS | 6564 | 2019-10-15 | Yes |
| 406-409 | BILLINGS | 425J | 2019-05-29 | Yes |
| 406-410 | HELENA | 6564 | — | Yes |
| 406-411 | XXXXXXXXXX | MULT | — | — |
| 406-412 | BILLINGS | 453F | 2017-05-22 | Yes |
| 406-413 | BILLINGS | 9636 | 2015-05-12 | Yes |
| 406-414 | BOZEMAN | 9636 | 2011-12-07 | Yes |
| 406-415 | DEER LODGE | 792K | 2010-04-09 | Yes |
| 406-416 | FORSYTH | 453F | 2020-06-17 | Yes |
| 406-417 | HELENA | 6010 | 2008-05-28 | Yes |
| 406-418 | COOKE CITY | 453F | 2019-08-20 | Yes |
| 406-419 | VICTOR | 453F | 2019-07-12 | Yes |
| 406-420 | BIGFORK | 792K | 2006-02-28 | Yes |
| 406-421 | SOMILES CY | 2251 | — | Yes |
| 406-422 | HELENA | 792K | — | Yes |
| 406-423 | HOBSON | 3310 | — | — |
| 406-424 | SHELBY | 3924 | 2001-11-12 | Yes |
| 406-425 | RED LODGE | 6564 | — | Yes |
| 406-426 | RED LODGE | 6564 | — | Yes |
| 406-427 | SO BROADUS | 2251 | — | — |
| 406-428 | GRASSRANGE | 2246 | — | Yes |
| 406-429 | WINNETT | 2246 | — | Yes |
| 406-430 | HELENA | 453F | — | Yes |
| 406-431 | HELENA | 6564 | — | — |
| 406-432 | DEVON | 2248 | — | — |
| 406-433 | SIDNEY | 7830 | — | — |
| 406-434 | SHELBY | 9636 | — | Yes |
| 406-435 | BILLINGS | 520K | — | Yes |
| 406-436 | BROADUS | 2251 | — | Yes |
| 406-437 | HELENA | 7229 | 2004-07-27 | Yes |
| 406-438 | HELENA | 6564 | 2014-02-06 | Yes |
| 406-439 | HELENA | 6010 | — | Yes |
| 406-440 | HELENA | 3924 | 2005-07-01 | Yes |
| 406-441 | HELENA | 9636 | — | — |
| 406-442 | HELENA | 9636 | — | — |
| 406-443 | HELENA | 9636 | — | — |
| 406-444 | HELENA | 9636 | — | — |
| 406-445 | RED LODGE | 9636 | — | Yes |
| 406-446 | RED LODGE | 9636 | — | Yes |
| 406-447 | HELENA | 9636 | — | Yes |
| 406-448 | NO POPLAR | 2247 | — | Yes |
| 406-449 | HELENA | 9636 | — | — |
| 406-450 | SHELBY | 6564 | — | Yes |
| 406-451 | BOZEMAN | 6529 | 2004-08-04 | Yes |
| 406-452 | GREATFALLS | 9636 | — | — |
| 406-453 | GREATFALLS | 9636 | — | — |
| 406-454 | GREATFALLS | 9636 | — | — |
| 406-455 | GREATFALLS | 9636 | — | Yes |
| 406-456 | SO CHESTER | 2257 | — | — |
| 406-457 | HELENA | 9636 | — | Yes |
| 406-458 | HELENA | 9636 | — | Yes |
| 406-459 | HELENA | 6564 | — | — |
| 406-460 | SHELBY | 6010 | — | Yes |
| 406-461 | HELENA | 6564 | — | — |
| 406-462 | WINIFRED | 2257 | — | — |
| 406-463 | POWER | 2255 | — | — |
| 406-464 | ROY | 2246 | — | Yes |
| 406-465 | HELENA | 6564 | — | — |
| 406-466 | CHOTEAU | 2255 | — | Yes |
| 406-467 | FAIRFIELD | 2255 | — | Yes |
| 406-468 | CASCADE | 9636 | — | Yes |
| 406-469 | PENDROY | 2255 | — | — |
| 406-470 | SHELBY | 6564 | — | Yes |
| 406-471 | KALISPELL | 6564 | 2005-06-01 | — |
| 406-472 | DUPUYER | 2255 | — | — |
| 406-473 | JUDITH GAP | 3310 | — | — |
| 406-474 | FLAXVILLE | 2247 | — | — |
| 406-475 | HELENA | 9636 | — | Yes |
| 406-476 | DUTTON | 9636 | — | Yes |
| 406-477 | LAME DEER | 2251 | — | Yes |
| 406-478 | SIDNEY | 6564 | — | Yes |
| 406-479 | BUTTE | 6564 | 2013-10-03 | Yes |
| 406-480 | SIDNEY | 6564 | — | Yes |
| 406-481 | MISSOULA | 6564 | 2023-06-21 | Yes |
| 406-482 | SIDNEY | 9636 | — | Yes |
| 406-483 | DAGMAR | 2247 | — | — |
| 406-484 | CROOKEDCRK | 2296 | — | Yes |
| 406-485 | CIRCLE | 2246 | — | Yes |
| 406-486 | FALLON | 2246 | — | — |
| 406-487 | SCOBEY | 2247 | — | Yes |
| 406-488 | SIDNEY | 7830 | — | — |
| 406-489 | SIDNEY | 6010 | — | Yes |
| 406-490 | BUTTE | 6564 | — | — |
| 406-491 | BUTTE | 6010 | — | Yes |
| 406-492 | AVON | 2235 | — | — |
| 406-493 | MISSOULA | 792K | — | Yes |
| 406-494 | BUTTE | 9636 | — | — |
| 406-495 | HELENA | 9636 | — | Yes |
| 406-496 | BUTTE | 9636 | — | Yes |
| 406-497 | BUTTE | 9636 | — | Yes |
| 406-498 | BUTTE | 6564 | — | — |
| 406-499 | SEELEYLAKE | 6010 | 2003-03-18 | 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.