All assignees
768 prefixes in 406 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 406-821 | DARBY | 9636 | — | Yes |
| 406-822 | SUPERIOR | 2235 | — | Yes |
| 406-823 | LIVINGSTON | 9636 | — | Yes |
| 406-824 | STIGNATIUS | 6010 | — | Yes |
| 406-825 | CLINTON | 2235 | — | Yes |
| 406-826 | PLAINS | 2235 | — | Yes |
| 406-827 | THOMPSNFLS | 2235 | — | Yes |
| 406-828 | ALZADA | 2251 | — | Yes |
| 406-829 | MISSOULA | 9636 | — | — |
| 406-830 | MISSOULA | 792K | 2007-02-06 | Yes |
| 406-831 | BILLINGS | 073H | 2016-12-21 | Yes |
| 406-832 | WISE RIVER | 2254 | — | — |
| 406-833 | RONAN | 6564 | — | Yes |
| 406-834 | JACKSON | 2254 | — | — |
| 406-835 | MELROSE | 2255 | — | — |
| 406-836 | GREATFALLS | 453F | — | Yes |
| 406-837 | BIGFORK | 2249 | — | Yes |
| 406-838 | COOKE CITY | 9636 | — | Yes |
| 406-839 | BILLINGS | 792K | 2006-09-30 | Yes |
| 406-840 | SILVERTIP | 453F | 2007-05-23 | Yes |
| 406-841 | HELENA | 9636 | — | Yes |
| 406-842 | SHERIDAN | 2255 | — | Yes |
| 406-843 | VIRGINIACY | 2255 | — | — |
| 406-844 | LAKESIDE | 2249 | — | Yes |
| 406-845 | CUT BANK | 792K | 2008-10-27 | Yes |
| 406-846 | DEER LODGE | 9636 | — | Yes |
| 406-847 | NOXON | 2235 | — | — |
| 406-848 | GARDINER | 9636 | — | Yes |
| 406-849 | ELMO | 2249 | — | Yes |
| 406-850 | BILLINGS | 6010 | — | Yes |
| 406-851 | MILES CITY | 6010 | — | Yes |
| 406-852 | MILES CITY | 6564 | — | Yes |
| 406-853 | MILES CITY | 6564 | — | Yes |
| 406-854 | MARION | 2249 | — | Yes |
| 406-855 | BILLINGS | 6010 | — | — |
| 406-856 | CUSTER | 2246 | — | — |
| 406-857 | SOMERS | 2249 | — | Yes |
| 406-858 | KALISPELL | 490J | — | Yes |
| 406-859 | PHILIPSBG | 2235 | — | — |
| 406-860 | BILLINGS | 6010 | — | — |
| 406-861 | BILLINGS | 6010 | — | Yes |
| 406-862 | WHITEFISH | 2249 | — | — |
| 406-863 | WHITEFISH | 2249 | — | Yes |
| 406-864 | S ALBERTON | 2235 | — | — |
| 406-865 | DILLON | 6564 | — | Yes |
| 406-866 | GREATFALLS | 9636 | — | Yes |
| 406-867 | BILLINGS | 700J | — | Yes |
| 406-868 | GREATFALLS | 6564 | — | — |
| 406-869 | BILLINGS | 4222 | — | — |
| 406-870 | GREATFALLS | 994E | — | Yes |
| 406-871 | KALISPELL | 6564 | 2006-06-15 | — |
| 406-872 | POLSON | 986F | 2007-10-15 | Yes |
| 406-873 | CUT BANK | 9636 | — | Yes |
| 406-874 | MILES CITY | 7830 | — | Yes |
| 406-875 | POMPESPLLR | 2250 | — | — |
| 406-876 | BILLINGS | 6564 | — | Yes |
| 406-877 | WEST BEACH | 1632 | — | — |
| 406-878 | GREATFALLS | 732J | 2013-03-01 | Yes |
| 406-879 | HAVRE | 6010 | 2009-11-11 | Yes |
| 406-880 | MISSOULA | 6564 | — | — |
| 406-881 | OLNEY | 2249 | — | Yes |
| 406-882 | EUREKARURL | 2242 | — | — |
| 406-883 | POLSON | 2249 | — | — |
| 406-884 | POLSON | 2249 | — | Yes |
| 406-885 | KALISPELL | 6564 | — | — |
| 406-886 | SWAN LAKE | 2249 | — | Yes |
| 406-887 | FINLEY PT | 2249 | — | Yes |
| 406-888 | W GLACIER | 9636 | — | Yes |
| 406-889 | EUREKARURL | 2242 | — | — |
| 406-890 | KALISPELL | 792K | — | Yes |
| 406-891 | BAKER | 6010 | — | Yes |
| 406-892 | COLUMBIFLS | 2249 | — | — |
| 406-893 | PEERLESS | 2247 | — | Yes |
| 406-894 | BILLINGS | 939H | — | Yes |
| 406-895 | OUTLOOK | 2247 | — | Yes |
| 406-896 | BILLINGS | 9636 | — | — |
| 406-897 | COLUMBIFLS | 792K | — | Yes |
| 406-898 | BOZEMAN | 792K | 2009-03-20 | Yes |
| 406-899 | GREATFALLS | 6010 | — | — |
| 406-900 | ENNIS | 9415 | 2017-09-29 | Yes |
| 406-901 | BILLINGS | 624H | 2021-04-14 | Yes |
| 406-902 | SHERIDAN | 9415 | 2018-11-27 | Yes |
| 406-905 | JOLIET | 453F | 2011-10-03 | Yes |
| 406-909 | COLUMBIFLS | 6564 | 2018-05-24 | Yes |
| 406-911 | XXXXXXXXXX | MULT | — | — |
| 406-913 | ROUNDUP | 6564 | — | Yes |
| 406-914 | LAMBERT | 6564 | — | Yes |
| 406-915 | SO WOLF PT | 6564 | — | Yes |
| 406-916 | HELENA | 6529 | 2017-03-24 | Yes |
| 406-918 | LIBBY | 6010 | 2026-01-15 | Yes |
| 406-919 | BELGRADE | 145J | 2019-03-04 | Yes |
| 406-920 | BOZEMAN | 6564 | — | Yes |
| 406-922 | BOZEMAN | 4222 | — | Yes |
| 406-923 | GREATFALLS | 939H | — | Yes |
| 406-924 | BELGRADE | 9415 | 2004-10-26 | Yes |
| 406-925 | DILLON | 6564 | — | Yes |
| 406-926 | MISSOULA | 792K | 2011-01-07 | Yes |
| 406-927 | BILLINGS | 6010 | 2010-07-23 | Yes |
| 406-928 | GRASSRANGE | 6564 | — | Yes |
| 406-929 | HUNGRYHORS | 453F | 2007-07-26 | 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.