All assignees
768 prefixes in 406 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 406-930 | BIG TIMBER | 6564 | — | Yes |
| 406-931 | BIG TIMBER | 6564 | — | Yes |
| 406-932 | BIG TIMBER | 2257 | — | Yes |
| 406-933 | HELENA | 9636 | — | Yes |
| 406-934 | MILES CITY | 743G | — | Yes |
| 406-935 | BROADUS | 6564 | — | Yes |
| 406-936 | CLYDE PARK | 994E | 2015-07-15 | Yes |
| 406-937 | SUNBURST | 2248 | — | — |
| 406-938 | ALZADA | 6564 | — | Yes |
| 406-939 | W GLENDIVE | 6564 | — | Yes |
| 406-940 | MOLT | 6010 | 2017-07-18 | Yes |
| 406-941 | W GLENDIVE | 6564 | — | Yes |
| 406-942 | GLASGOW | 6564 | 2009-10-23 | Yes |
| 406-943 | SIDNEY | 9415 | 2003-01-09 | Yes |
| 406-944 | MILES CITY | 9415 | 2003-01-09 | Yes |
| 406-945 | HAVRE | 6010 | — | Yes |
| 406-946 | LIVINGSTON | 9415 | 2003-01-09 | Yes |
| 406-947 | MUSSELSHLL | 2246 | — | — |
| 406-948 | GLENDIVE | 9415 | 2003-01-09 | Yes |
| 406-949 | TOWNSEND | 6010 | — | Yes |
| 406-950 | — | — | ||
| 406-951 | MILES CITY | 6010 | — | Yes |
| 406-952 | GREATFALLS | 624H | — | Yes |
| 406-953 | HARDIN | 443B | — | Yes |
| 406-954 | ROY | 6564 | — | Yes |
| 406-955 | KALISPELL | 6564 | 2023-12-04 | Yes |
| 406-956 | BAKER | 6010 | 2010-10-20 | Yes |
| 406-957 | TERRY | 6564 | — | Yes |
| 406-958 | — | — | ||
| 406-959 | — | — | ||
| 406-960 | DILLON | 9415 | 2003-01-09 | Yes |
| 406-961 | HAMILTON | 9636 | — | Yes |
| 406-962 | JOLIET | 9636 | — | Yes |
| 406-963 | FROIDRURAL | 2247 | — | Yes |
| 406-964 | GREATFALLS | 9636 | — | Yes |
| 406-965 | GREATFALLS | 588H | — | Yes |
| 406-966 | SHELBY | 9415 | 2003-01-09 | Yes |
| 406-967 | WORDEN | 2250 | — | Yes |
| 406-968 | LEWISTOWN | 321J | 2003-01-09 | Yes |
| 406-969 | BILLINGS | 622J | — | Yes |
| 406-970 | BILLINGS | 508J | 2016-06-03 | Yes |
| 406-971 | PLEVNA | 6564 | — | Yes |
| 406-972 | WCAMPCROOK | 1689 | — | — |
| 406-973 | SIDNEY | 6564 | — | Yes |
| 406-974 | CIRCLE | 6564 | — | Yes |
| 406-975 | EKALAKA | 6564 | — | Yes |
| 406-976 | XXXXXXXXXX | MULT | — | — |
| 406-977 | JORDAN | 6564 | — | Yes |
| 406-978 | BAKER | 6564 | — | Yes |
| 406-979 | RICHEY | 6564 | — | Yes |
| 406-980 | TOWNSEND | 6564 | — | Yes |
| 406-981 | SOMILES CY | 6564 | — | Yes |
| 406-982 | YELLOW BAY | 2249 | — | Yes |
| 406-983 | ASHLAND | 6564 | — | Yes |
| 406-984 | BIRNEY | 2251 | — | Yes |
| 406-987 | GLENDIVE | 6564 | — | Yes |
| 406-988 | DILLON | 9415 | 2005-01-07 | Yes |
| 406-989 | W GLENDIVE | 6010 | — | Yes |
| 406-990 | LAME DEER | 6010 | 2020-05-12 | Yes |
| 406-991 | MARION | 453F | 2007-10-11 | Yes |
| 406-992 | HELENA | 453F | 2008-08-26 | Yes |
| 406-993 | BIG SKY | 2255 | — | Yes |
| 406-994 | BOZEMAN | 9636 | — | — |
| 406-995 | BIG SKY | 2255 | — | Yes |
| 406-996 | HELENA | 792K | 2011-01-10 | Yes |
| 406-997 | FROMBERG | 7421 | 2024-01-24 | Yes |
| 406-998 | BILLINGS | 588H | 2015-08-26 | Yes |
| 406-999 | BIG SKY | 746D | 2006-07-11 | — |
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.