The 720 area code covers the same area as 303, including Denver, Longmont and 9 more places in Colorado.
Area code 720 is in Colorado, on Mountain Time. In the 720 area, phone numbers are given out most in Denver County, then Boulder and Weld counties. It has been in service since June 1, 1998. 303 and 983 cover the same area, so two neighbours can have different area codes.
- Where
- 6 counties in Colorado, mostly Denver County, Boulder County and Weld County
- Time zone
- Mountain Time
- In service since
- June 1, 1998
- Shares its area with
- 303 (since 1947) and 983 (since 2022)
- Prefixes in use
- 785
- How to dial
- Local calls need all 10 digits: 720-555-0142.
Find out who called you from a 720 number.
Enter the full 10-digit number to see who it is listed to and the city and state on the listing. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup. To see whether it is a mobile, a landline or a VoIP line, use our free VoIP checker. To see which carrier a (720) number is on today, use our free carrier lookup.
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Denver holds 86% of the phone prefixes in area code 720.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 785 prefixes in use shows where 720 numbers are actually given out.
- Denver678 prefixes, 86%
- Longmont39 prefixes, 5%
- Fort Lupton14 prefixes, 2%
- Georgetown11 prefixes, 1%
- Keenesburg9 prefixes, 1%
- Hudson8 prefixes, 1%
- Deer Trail3 prefixes, <1%
- Strasburg1 prefix, <1%
Also served: Bennett, Byers and Roggen.
T-Mobile holds the most phone number prefixes in area code 720: 132 of 785.
NANPA, which runs the North American numbering plan, assigns each prefix (the three digits after the area code) to one carrier. Here is how the 785 prefixes in use in 720 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| T-MobileMobile network | 132 | 17% |
| Qwest (Lumen)Lumen's landline company | 103 | 13% |
| AT&T MobilityMobile network | 92 | 12% |
| Level 3 (Lumen)Lumen's business and wholesale network | 63 | 8% |
| BandwidthSupplies numbers to VoIP and app-based phone services | 55 | 7% |
| Teleport (AT&T)AT&T's business phone network | 31 | 4% |
| 38 other carriers | 309 | 39% |
83% of these prefixes are pooled, which means the blocks of 1,000 numbers inside them can belong to other carriers. Any number can also have been moved to another carrier since, so this shows who holds the prefixes, not who serves a given number.
Want the carrier of one exact number? Our free carrier lookup checks it, because numbers move between carriers.
Source: NANPA central office code assignments, October 1, 2026.
720 started in 1998 as an overlay on 303, and its ground has not changed since.
1998
720 starts on June 1, 1998, as an overlay on 303: new numbers on the same ground.
A 720 number on your screen can still be a scam, because caller ID is easy to fake.
- Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
- Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
- Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
- Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.
The area codes closest to 720 are 970, 719 and 308.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
Colorado has 5 other area codes.
These are the questions people ask most about area code 720.
Where is area code 720?
720 covers Denver, Longmont, Fort Lupton and Keenesburg and 7 more places in Colorado. In the 720 area, phone numbers are given out most in Denver County, then Boulder and Weld counties.
What state is area code 720 in?
Colorado. 720 is a Colorado area code on Mountain Time.
What cities use area code 720?
The places holding the most 720 prefixes are Denver, Longmont, Fort Lupton, Keenesburg, Hudson, Georgetown, Deer Trail and Strasburg, out of 11 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 720?
No single phone company owns 720. NANPA's records show T-Mobile holds the most 720 prefixes, 132 of 785, followed by Qwest (Lumen) and AT&T Mobility. Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 720 in?
720 is on Mountain Time.
When did area code 720 start?
720 went into service on June 1, 1998, as an overlay on 303: new numbers for the same area.
Is 720 the same area as 303 and 983?
Yes. 303 (since 1947) and 983 (since 2022) cover the same ground as 720. Nobody's number changed when they were added; new lines simply get whichever code has numbers left, so two neighbours can have different codes.
How do I dial a 720 number?
Local calls need all 10 digits: 720-555-0142.
Is 720 a toll-free number?
No. 720 is a regular area code for Denver and Longmont in Colorado, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.
What area codes are near 720?
The closest are 970/748 (Fort Collins, Colorado), 719 (Colorado Springs, Colorado) and 308 (Grand Island, Nebraska), measured between the centres of each area.
Who called me from a 720 number?
Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.
Is area code 720 a scam?
720 is a real Colorado area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.
Put this lookup on your site: our free area code widget takes two lines of code and shows any US area code's state, time zone and local time.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.