Colorado area codes
Colorado uses 6 area codes. The oldest is 303, in service since 1947; the newest is 748, from 2025. Across them 3,077 of 4,716 possible number blocks are allocated, 65.2% of capacity. 970, 720 and 303 are at or past 95%, which is why new numbers there come from overlays rather than the original code. Lumen holds 38.4% of the 3,077 assigned blocks across the state, ahead of Verizon at 12.3%; a further 9.0% sits with CLEC and VoIP holders outside the national carriers. In the 33 days to 30 October 2026, FTC complaints named a Colorado caller ID 4,281 times – 1.9% of all complaints in the window, most often 720 with 1,150 (24th of 422 nationally). NANPA records 236 rate centers across the state's codes, and local calls take all ten digits.
All 6 codes
| Code | In service | Blocks used | Largest holder | Complaints | Shares area with |
|---|---|---|---|---|---|
| 303 | 1947 | 784/786 | Lumen 64.8% | 927 | 720, 983 |
| 719 | 1988 | 665/786 | Lumen 36.1% | 958 | no overlay |
| 720 | 1998 | 785/786 | Lumen 21.7% | 1,150 | 303, 983 |
| 748 | 2025 | 9/786 | Onvoy 55.6% | – | 970 |
| 970 | 1995 | 786/786 | Lumen 33.7% | 1,101 | 748 |
| 983 | 2022 | 48/786 | Other CLEC / VoIP 39.6% | 145 | 303, 720 |
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 Colorado’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
Who holds the number blocks
Counted from every assigned block in the state: 3,077 blocks, each with the holder NANPA recorded for it. Percentages are measured, not estimated.
| Holder | Blocks | Share of Colorado | Largest in |
|---|---|---|---|
| Lumen | 1,183 | 38.4% | 4 codes |
| Verizon | 378 | 12.3% | – |
| AT&T | 335 | 10.9% | – |
| T-Mobile | 312 | 10.1% | – |
| Other CLEC / VoIP | 278 | 9% | 1 code |
| Onvoy | 263 | 8.5% | 1 code |
| Bandwidth | 94 | 3.1% | – |
| Comcast | 43 | 1.4% | – |
| Spok | 36 | 1.2% | – |
| Allstream | 27 | 0.9% | – |
| Charter | 27 | 0.9% | – |
| Peerless | 26 | 0.8% | – |
“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 Colorado codes
FTC Do Not Call complaints where the caller ID shown was a Colorado 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.
| Code | Complaints | National rank |
|---|---|---|
| 720 | 1,150 | #24 of 422 |
| 970 | 1,101 | #28 of 422 |
| 719 | 958 | #46 of 422 |
| 303 | 927 | #53 of 422 |
| 983 | 145 | #360 of 422 |
What people said the calls were about
- Other – 431
- Reducing your debt (credit cards, mortgage, student loans) – 273
- Dropped call or no message – 126
- Calls pretending to be government, businesses, or family and friends – 117
Topics as the complainant chose them, for the codes where the FTC published a topic.
How Colorado got its codes
1 in the 1940s, 1 in the 1980s, 2 in the 1990s, 2 in the 2020s. Each code after the first was split off from or overlaid on one already in service.
- 1947 303 goes into service.
- 1988 719 goes into service, split from or overlaid on 303.
- 1995 970 goes into service, split from or overlaid on 303.
- 1998 720 goes into service, split from or overlaid on 303.
- 2022 983 goes into service, split from or overlaid on 303.
- 2025 748 goes into service, split from or overlaid on 970.
Time zones
Colorado is in Mountain time.
Frequently asked about Colorado area codes
How many area codes does Colorado have?
6 in service. They are 303, 719, 720, 748, 970 and 983.
What is the oldest area code in Colorado?
303, in service since 1947. Every later code in the state was split off from or overlaid on an existing one.
What is the newest area code in Colorado?
748, from 2025, overlaying 970.
Is Colorado running out of numbers?
970, 720 and 303 are at or past 95% of capacity, but NANPA has not opened relief planning for them, so no new code is announced.
What time zone is Colorado in?
Mountain time.
Which Colorado area code gets the most spam complaints?
720 – 1,150 FTC complaints in the 33 days to 30 October 2026, 24th 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 Colorado numbers?
Lumen, with 38.4% of the 3,077 blocks assigned across Colorado, ahead of Verizon at 12.3%. 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 Colorado?
Yes. Every code in the state is in an overlay or 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.