Montana area codes
Montana uses 1 area code. Its code 406 has been in service since 1947. It has 754 of its 786 possible number blocks allocated, 95.9% of capacity. 406 is at or past 95%, which is why new numbers there come from overlays rather than the original code. Across the state no single national carrier holds the most blocks: 34.6% sits with CLEC and VoIP holders counted together, ahead of Lumen at 24.5%. In the 33 days to 30 October 2026, FTC complaints named a Montana caller ID 647 times – 0.3% of all complaints in the window, most often 406 with 647 (161st of 422 nationally). NANPA records 260 rate centers in 406, and local calls take all ten digits.
The Montana area code
| Code | In service | Blocks used | Largest holder | Complaints | Shares area with |
|---|---|---|---|---|---|
| 406 | 1947 | 754/786 | Other CLEC / VoIP 34.6% | 647 | no overlay |
Block share is share of allocated number blocks, not of subscribers. Complaint counts cover 28 Sep – 30 Oct 2026 and reflect spoofed caller IDs as much as real calls.
How full Montana’s codes are
A code holds at most 786 blocks of 10,000 numbers each. When a code fills up, the administrator does not reclaim numbers – it adds an overlay, and from then on new numbers in the same area come from the new code.
Full or nearly full
Most room left
Who holds the number blocks
Counted from every assigned block in the state: 754 blocks, each with the holder NANPA recorded for it. Percentages are measured, not estimated.
| Holder | Blocks | Share of Montana | Largest in |
|---|---|---|---|
| Other CLEC / VoIP | 261 | 34.6% | 1 code |
| Lumen | 185 | 24.5% | – |
| Verizon | 123 | 16.3% | – |
| AT&T | 81 | 10.7% | – |
| Onvoy | 43 | 5.7% | – |
| Charter | 28 | 3.7% | – |
| T-Mobile | 7 | 0.9% | – |
| Bandwidth | 4 | 0.5% | – |
| Ziply Fiber | 4 | 0.5% | – |
| Allstream | 4 | 0.5% | – |
| Telnyx | 4 | 0.5% | – |
| TDS | 2 | 0.3% | – |
“Other CLEC / VoIP” is not one company: it is every holder outside the national carriers counted together, which is what resellers and app-based numbers look like in the records. This is allocation, not subscribers.
Spam complaints naming Montana codes
FTC Do Not Call complaints where the caller ID shown was a Montana number, 28 Sep – 30 Oct 2026 (33 days). Caller IDs on spam calls are routinely faked, so these are complaints about the code, not calls proven to come from it.
Time zones
Montana is in Mountain time.
Frequently asked about Montana area codes
How many area codes does Montana have?
1 in service. That code is 406.
What is the oldest area code in Montana?
406, in service since 1947.
Is Montana running out of numbers?
406 is at or past 95% of capacity, but NANPA has not opened relief planning for it, so no new code is announced.
What time zone is Montana in?
Mountain time.
Which Montana area code gets the most spam complaints?
406 – 647 FTC complaints in the 33 days to 30 October 2026, 161st of 422 codes nationally. Those are complaints about the caller ID shown, and spam callers routinely fake a local-looking number, so this says the code is imitated often, not that the calls come from there.
Which carrier holds the most Montana numbers?
No one carrier does. 34.6% of the 754 number blocks assigned across Montana are held by CLEC and VoIP providers outside the national carriers – resellers and app-based numbers look like this in the records. The largest named carrier is Lumen with 24.5%. This is allocation of blocks by the numbering administrator, not a count of subscribers – people keep their numbers when they switch carriers.
Do you have to dial 10 digits in Montana?
Yes. The code is in a ten-digit dialing area, so a local call needs the area code too. Dialing seven digits reaches a recording, not a wrong number.
Sources and verification
- NANPA – NPA Database (npa_report.csv), file date 11/01/2026, retrieved Nov 1, 2026
- NANPA – CO Code Assignment Records, All States (utilized), file updated 11/01/2026, retrieved Nov 1, 2026
- FTC – Do Not Call Reported Calls Data, 28 Sep – 30 Oct 2026, retrieved Nov 1, 2026
Figures on this page are counted from those files, not copied from other sites. Spotted an error? Request a correction. How we collect and check: methodology.