All assignees
525 prefixes in 307 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 307-400 | CHEYENNE | 145J | 2020-01-24 | Yes |
| 307-401 | TORRINGTON | 6010 | — | Yes |
| 307-402 | MT VIEW | 6010 | 2021-11-05 | Yes |
| 307-403 | MORAN | 081F | 2022-02-22 | Yes |
| 307-404 | MEDICINBOW | 6010 | 2018-05-23 | Yes |
| 307-405 | WBLLFOURCH | 450F | 2023-05-24 | Yes |
| 307-406 | — | — | ||
| 307-407 | WSPEARFISH | 450F | 2020-08-10 | Yes |
| 307-408 | LYMAN | 6010 | 2021-11-05 | Yes |
| 307-409 | LA GRANGE | 6010 | 2018-02-20 | Yes |
| 307-410 | POWELL | 6529 | 2022-03-22 | Yes |
| 307-411 | XXXXXXXXXX | MULT | — | — |
| 307-412 | CHEYENNE | 7421 | 2022-09-23 | Yes |
| 307-413 | JACKSON | 6010 | 2001-01-29 | — |
| 307-414 | CHEYENNE | 581H | 2015-08-24 | Yes |
| 307-415 | CHEYENNE | 732J | 2023-03-03 | Yes |
| 307-416 | PINEDALE | 9416 | 2023-05-24 | Yes |
| 307-417 | RAWLINS | 450F | — | Yes |
| 307-418 | JACKSON | 6010 | 2023-06-09 | Yes |
| 307-419 | CODY | 6529 | 2022-03-24 | Yes |
| 307-420 | LINGLE | 450F | 2023-05-24 | Yes |
| 307-421 | CHEYENNE | 6566 | — | — |
| 307-422 | CHUGWATER | 2289 | — | — |
| 307-423 | BUFFALO | 081F | 2021-11-05 | Yes |
| 307-424 | LAKE | 450F | 2023-05-24 | Yes |
| 307-425 | BUFFALO | 268A | 2011-03-30 | — |
| 307-426 | CHEYENNE | 792K | 2007-05-22 | Yes |
| 307-427 | MAMMOTH | 450F | 2023-05-24 | Yes |
| 307-428 | DOUGLAS | 6529 | 2023-12-01 | Yes |
| 307-429 | SHERIDAN | 081F | 2013-05-23 | Yes |
| 307-430 | OLDFATHFUL | 450F | 2023-12-11 | Yes |
| 307-431 | WORLAND | 6566 | — | Yes |
| 307-432 | CHEYENNE | 9636 | — | Yes |
| 307-433 | CHEYENNE | 9636 | — | Yes |
| 307-434 | GILLETTE | 450F | 2024-02-05 | Yes |
| 307-435 | SHERIDAN | 6529 | 2025-12-03 | Yes |
| 307-436 | GLENROCK | 9636 | — | — |
| 307-437 | MIDWEST | 3410 | — | — |
| 307-438 | LANDER | 6566 | 2007-06-19 | Yes |
| 307-439 | CASPER | 9416 | — | Yes |
| 307-440 | BASIN | 009E | — | Yes |
| 307-441 | CASPER | 6566 | — | Yes |
| 307-442 | EVANSTON | 450F | 2024-02-29 | Yes |
| 307-443 | CHEYENNE | 939H | 2019-06-18 | Yes |
| 307-444 | EVANSTON | 3880 | — | — |
| 307-445 | KEMMERER | 450F | 2021-02-05 | Yes |
| 307-446 | WSPEARFISH | 450F | 2023-05-24 | Yes |
| 307-447 | SARATOGA | 9416 | 2015-10-08 | Yes |
| 307-448 | ROCK SPG | 6566 | 2011-05-12 | Yes |
| 307-449 | ROCK SPG | 6010 | — | Yes |
| 307-450 | DUBOIS | 013B | — | — |
| 307-451 | ROCK SPG | 197D | 2024-05-06 | Yes |
| 307-452 | CASPER | 450F | 2024-05-30 | Yes |
| 307-453 | JACKSON | 450F | 2024-06-06 | Yes |
| 307-454 | RIVERTON | 450F | 2024-06-07 | Yes |
| 307-455 | DUBOIS | 2291 | — | — |
| 307-456 | BIG PINEY | 9416 | 2019-07-22 | Yes |
| 307-457 | GAS HILLS | 3410 | — | — |
| 307-458 | CASPER | 490J | 2021-12-10 | Yes |
| 307-459 | CHEYENNE | 9416 | 2002-06-11 | Yes |
| 307-460 | LARAMIE | 9416 | 2002-06-11 | Yes |
| 307-461 | SHERIDAN | 9416 | 2002-06-11 | Yes |
| 307-462 | CASPER | 9416 | 2002-06-11 | Yes |
| 307-463 | RIVERTON | 9416 | 2002-06-11 | Yes |
| 307-464 | WRIGHT | 9636 | — | Yes |
| 307-465 | NEWCASTLE | 3410 | — | — |
| 307-466 | GREENRIVER | 6566 | — | Yes |
| 307-467 | HULETT | 3410 | — | — |
| 307-468 | UPTON | 3410 | — | — |
| 307-469 | HYATTVILLE | 2296 | — | — |
| 307-470 | — | — | ||
| 307-471 | LUSK | 6010 | 2024-09-10 | Yes |
| 307-472 | CASPER | 9636 | — | — |
| 307-473 | CASPER | 9636 | — | Yes |
| 307-474 | CODY | 450F | 2024-12-12 | Yes |
| 307-475 | CHEYENNE | 073H | 2016-12-21 | Yes |
| 307-476 | LARAMIE | 450F | 2025-01-09 | Yes |
| 307-477 | CHEYENNE | 013B | — | — |
| 307-478 | LA GRANGE | 6529 | 2025-02-05 | Yes |
| 307-479 | POWELL | 450F | 2025-02-12 | Yes |
| 307-480 | THERMOPOLS | 6010 | 2005-06-15 | Yes |
| 307-481 | LUSK | 450F | 2007-03-14 | Yes |
| 307-482 | WHEATLAND | 6529 | 2025-04-08 | Yes |
| 307-483 | RAWLINS | 6010 | 2025-04-30 | Yes |
| 307-484 | CHEYENNE | 700J | 2026-01-07 | Yes |
| 307-485 | CASPER | 6529 | 2025-05-06 | Yes |
| 307-486 | CROWHEART | 2291 | — | — |
| 307-487 | GILLETTE | 6566 | 2018-10-09 | Yes |
| 307-488 | LANDER | 081F | 2018-04-19 | Yes |
| 307-489 | SHIRLEBSIN | 6010 | 2018-05-30 | Yes |
| 307-490 | UPTON | 792K | 2026-02-25 | Yes |
| 307-493 | URIE | 1772 | 2026-09-11 | Yes |
| 307-496 | LAKE | 114J | 2026-03-31 | Yes |
| 307-497 | EVANSTON | 2290 | — | — |
| 307-499 | LYMAN | 1772 | 2026-09-11 | Yes |
| 307-500 | BORDER | 450F | 2021-02-05 | Yes |
| 307-507 | CHEYENNE | 953H | 2025-04-03 | Yes |
| 307-509 | CHEYENNE | 081F | 2008-09-05 | Yes |
| 307-511 | XXXXXXXXXX | MULT | — | — |
| 307-514 | CHEYENNE | 792K | — | 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.