All assignees
768 prefixes in 406 · initial assignments from the NANPA CO code file, 09/17/2026
| NPA-NXX | Rate center | OCN | Assigned | Pooled |
|---|---|---|---|---|
| 406-200 | BILLINGS | 771G | 2012-04-17 | Yes |
| 406-201 | FORSYTH | 6010 | 2003-01-21 | Yes |
| 406-202 | HELENA | 6010 | 2001-04-18 | Yes |
| 406-203 | MISSOULA | 9415 | — | Yes |
| 406-204 | HELENA | 9415 | — | Yes |
| 406-205 | GREATFALLS | 9415 | — | Yes |
| 406-206 | BILLINGS | 9415 | — | — |
| 406-207 | MISSOULA | 6010 | 2001-04-18 | Yes |
| 406-208 | BILLINGS | 6010 | 2001-04-18 | Yes |
| 406-209 | BOZEMAN | 6010 | 2001-04-18 | Yes |
| 406-210 | SEELEYLAKE | 6564 | — | Yes |
| 406-211 | XXXXXXXXXX | MULT | — | — |
| 406-212 | KALISPELL | 6010 | 2001-04-18 | Yes |
| 406-213 | COLSTRIP | 9415 | 2003-05-06 | Yes |
| 406-214 | MISSOULA | 6564 | — | Yes |
| 406-215 | MISSOULA | 622J | — | Yes |
| 406-216 | GREATFALLS | 3924 | — | Yes |
| 406-217 | GREATFALLS | 6564 | — | Yes |
| 406-218 | MISSOULA | 6529 | 2004-08-03 | Yes |
| 406-219 | BOZEMAN | 994E | 2003-02-13 | Yes |
| 406-220 | LIVINGSTON | 6010 | — | Yes |
| 406-221 | BUTTE | 453F | 2003-02-13 | Yes |
| 406-222 | LIVINGSTON | 9636 | — | — |
| 406-223 | LIVINGSTON | 6564 | — | — |
| 406-224 | LIVINGSTON | 6564 | — | Yes |
| 406-225 | BOULDER | 9636 | — | Yes |
| 406-226 | EGLACIERPK | 9636 | — | Yes |
| 406-227 | HELENA | 9636 | — | — |
| 406-228 | GLASGOW | 2247 | — | Yes |
| 406-229 | CUT BANK | 6010 | 2003-01-20 | Yes |
| 406-230 | GLASGOW | 6564 | — | Yes |
| 406-231 | GREATFALLS | 6010 | 2001-07-12 | Yes |
| 406-232 | MILES CITY | 9636 | — | — |
| 406-233 | MILES CITY | 9636 | — | Yes |
| 406-234 | MILES CITY | 7830 | — | — |
| 406-235 | WOLF CREEK | 9636 | — | Yes |
| 406-236 | NEIHART | 2255 | — | — |
| 406-237 | BILLINGS | 9636 | — | — |
| 406-238 | BILLINGS | 9636 | — | — |
| 406-239 | MISSOULA | 6010 | — | Yes |
| 406-240 | MISSOULA | 6010 | — | — |
| 406-241 | MISSOULA | 6010 | — | Yes |
| 406-242 | THOMPSNFLS | 6010 | 2003-03-18 | Yes |
| 406-243 | MISSOULA | 9636 | — | — |
| 406-244 | POTOMAC | 2235 | — | — |
| 406-245 | BILLINGS | 9636 | — | — |
| 406-246 | DIXON | 2235 | — | — |
| 406-247 | BILLINGS | 9636 | — | Yes |
| 406-248 | BILLINGS | 9636 | — | Yes |
| 406-249 | KALISPELL | 6564 | — | — |
| 406-250 | KALISPELL | 6564 | — | — |
| 406-251 | MISSOULA | 9636 | — | — |
| 406-252 | BILLINGS | 9636 | — | — |
| 406-253 | KALISPELL | 6010 | — | — |
| 406-254 | BILLINGS | 9636 | — | — |
| 406-255 | BILLINGS | 9636 | — | — |
| 406-256 | BILLINGS | 9636 | — | — |
| 406-257 | KALISPELL | 2249 | — | — |
| 406-258 | MISSOULA | 9636 | — | Yes |
| 406-259 | BILLINGS | 9636 | — | — |
| 406-260 | KALISPELL | 6010 | — | Yes |
| 406-261 | KALISPELL | 6010 | — | Yes |
| 406-262 | HAVRE | 9636 | — | Yes |
| 406-263 | GLASGOW | 443B | — | — |
| 406-264 | FORT SHAW | 2255 | — | — |
| 406-265 | HAVRE | 9636 | — | — |
| 406-266 | TOWNSEND | 9636 | — | Yes |
| 406-267 | DIVIDE | 2254 | — | — |
| 406-268 | GREATFALLS | 9636 | — | Yes |
| 406-269 | ST REGIS | 6010 | 2010-10-12 | Yes |
| 406-270 | KALISPELL | 6564 | — | — |
| 406-271 | CONRAD | 3924 | — | Yes |
| 406-272 | BILLINGS | 453F | — | Yes |
| 406-273 | MISSOULA | 9636 | — | Yes |
| 406-274 | MISSOULA | 771G | — | Yes |
| 406-275 | PABLO | 2252 | — | — |
| 406-276 | LIMA | 2255 | — | Yes |
| 406-277 | BELT | 2255 | — | — |
| 406-278 | CONRAD | 9636 | — | Yes |
| 406-279 | VALIER | 2255 | — | — |
| 406-280 | ST REGIS | 6010 | 2003-03-18 | Yes |
| 406-281 | BILLINGS | 771G | — | Yes |
| 406-282 | MANHATTAN | 9636 | — | Yes |
| 406-283 | LIBBY | 4322 | — | Yes |
| 406-284 | MANHATTAN | 9636 | — | Yes |
| 406-285 | THREEFORKS | 9636 | — | Yes |
| 406-286 | RESERVE | 2247 | — | Yes |
| 406-287 | WHITEHALL | 9636 | — | Yes |
| 406-288 | DRUMMOND | 2235 | — | — |
| 406-289 | CONRAD | 6010 | — | Yes |
| 406-290 | COLUMBUS | 453F | 2007-03-14 | Yes |
| 406-291 | LIBBY | 6564 | — | Yes |
| 406-292 | JOPLIN | 2257 | — | Yes |
| 406-293 | LIBBY | 4322 | — | Yes |
| 406-294 | BILLINGS | 4222 | — | — |
| 406-295 | TROY | 4322 | — | Yes |
| 406-296 | EUREKA | 4322 | — | Yes |
| 406-297 | EUREKARURL | 3959 | — | — |
| 406-298 | COLUMBUS | 6564 | — | Yes |
| 406-299 | BUTTE | 9415 | 2003-01-23 | 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.