Introduction
The 720 area code serves the Denver Metropolitan Area in Colorado, covering Denver, Aurora, Boulder, and dozens of Front Range suburbs. It runs as a full overlay of area code 303 and shares the same territory. This guide covers every city 720 serves, its Mountain Time Zone, its history, and how to get a virtual 720 number in minutes through CallMama.
Key Takeaways
- The 720 area code is a full overlay of 303, covering Denver, Aurora, Boulder, Lakewood, and dozens more Front Range communities.
- Every city in the 720 area code runs on Mountain Time — UTC-7 in winter, UTC-6 during daylight saving.
- 720 was created in 1998 and launched in 1999 to relieve number exhaustion in the fast-growing Denver metro.
- Scammers frequently spoof 720 numbers — common scams include IRS threats, Social Security fraud, and utility shutoff calls.
- You can get a virtual 720 phone number from anywhere in the world through CallMama — no Colorado address required.
What Is the 720 Area Code?
The 720 area code is a NANP geographic area code assigned to the Denver Metropolitan Area. It runs as a full overlay of area code 303, so both codes serve the exact same territory. 720 was approved in 1998 and launched in 1999, after cell phones and dial-up internet pushed the 303 number supply toward exhaustion. Regulators chose an overlay instead of a geographic split so no resident had to change their existing number.
The 720 region anchors three major cities and a wide ring of fast-growing suburbs:
- Denver — Colorado's capital and largest city, the Mile High City, and a major hub for technology, aerospace, energy, healthcare, and finance.
- Aurora — Colorado's second-largest city, home to Buckley Space Force Base and a growing tech and logistics economy.
- Boulder — home to the University of Colorado, NCAR, and NIST, and one of the most innovation-driven cities in the country.
- Front Range suburbs — a dense ring of communities that together form one of America's most dynamic metro regions.
720 Area Code Quick Facts
| Detail | Information |
|---|---|
| Area Code | 720 |
| State | Colorado (CO) |
| Region | Denver Metropolitan Area — full geographic overlay of 303 |
| Major Cities | Denver, Aurora, Boulder, Lakewood, Arvada, Westminster, Thornton, Centennial, Broomfield, Englewood, Greenwood Village, Highlands Ranch, Littleton, Parker, Castle Rock, Longmont, Louisville, Lafayette, Superior, Commerce City |
| Time Zone | Mountain Time (MST/MDT) |
| UTC Offset | UTC-7 (MST) / UTC-6 (MDT) |
| Established | 1998/1999 (overlay of 303) |
| Overlay Partner | 303 (same geographic territory) |
| Country | United States |
Where Is the 720 Area Code Located?
The 720 area code covers the Denver Metropolitan Area, the core of Colorado's Front Range Urban Corridor along the eastern foothills of the Rockies. Its boundaries are:
- Counties served: Denver, Jefferson, Arapahoe, Adams, Douglas, Boulder, and Broomfield.
- North and west: bordered by area code 970 (Fort Collins, Grand Junction, western Colorado).
- South: bordered by area code 719 (Colorado Springs, Pueblo, southeastern Colorado).
- East: the Great Plains, where Colorado borders Kansas and Nebraska.
Because 720 is a full overlay of 303, there are no 720-only or 303-only communities — every neighborhood in the Denver metro receives both codes. The shared territory runs from Longmont in the north, through Boulder and downtown Denver, south to Highlands Ranch and the Tech Center corridor, and out to Castle Rock at the edge of the metro. For a look at another fast-growing western metro, see our 725 area code guide.
Major Cities and Communities in the 720 Area Code
| City / Community | County | Notable For |
|---|---|---|
| Denver | Denver (City & County) | Colorado's capital and largest city; Mile High City (5,280 ft); Colorado State Capitol; Denver International Airport (DEN); 16th Street Mall; LoDo (Lower Downtown); Coors Field (Colorado Rockies); Empower Field at Mile High (Broncos); Ball Arena (Nuggets, Avalanche); Denver Art Museum; Denver Museum of Nature & Science; Denver Zoo; Washington Park; Denver Botanic Gardens; Union Station; RiNo (River North Arts District); Larimer Square; major tech, aerospace, energy, and financial services hub |
| Aurora | Arapahoe / Adams / Douglas | Colorado's third-largest city and largest suburb; Buckley Space Force Base (formerly Buckley AFB); Anschutz Medical Campus (one of the largest academic medical campuses in the nation — UCHealth, Children's Hospital Colorado, University of Colorado Hospital, VA Eastern Colorado Healthcare System); Aurora Reservoir; Stanley Marketplace; significant immigrant and international community; growing tech and logistics sector |
| Boulder | Boulder | University of Colorado Boulder (flagship state university; ranked research institution); Pearl Street Mall pedestrian dining and shopping district; National Center for Atmospheric Research (NCAR); National Institute of Standards and Technology (NIST); NOAA Earth System Research Laboratories; Google Boulder; Twitter (X) Boulder; Naropa University; Flatirons (iconic rock formations and hiking); outdoor recreation capital of Colorado; consistently ranked among the best places to live in the US; Boulder Farmers Market; Chautauqua Park |
| Lakewood | Jefferson | Colorado's fourth-largest city; Belmar shopping and entertainment district; Jefferson County government hub; Colorado Mills outlet mall; William Frederick Hayden Park; Jewell Wetlands; Red Rocks Community College; scenic Jefferson County Open Space parks |
| Arvada | Jefferson / Adams | Olde Town Arvada historic district (dining, arts, boutiques); Arvada Center for the Arts and Humanities; Ralston Creek trail system; Gold Strike Park; convenient light rail access to downtown Denver |
| Westminster | Adams / Jefferson | Promenade Shops at Orchard Town Center; Westminster City Park; Butterfly Pavilion (invertebrate zoo); Front Range Community College; outdoor recreation along the Clear Creek corridor; growing mixed-use development along the U.S. 36 BRT corridor |
| Thornton | Adams | One of Colorado's fastest-growing cities; Margaret W. Carpenter Recreation Center; Trail Winds Recreation Center; Thorncreek Golf Course; extensive trail system along the South Platte River corridor |
| Centennial | Arapahoe | One of the largest planned cities in US history (incorporated 2001); Centennial Airport (one of the busiest general aviation airports in the US); Streets at SouthGlenn; Denver Tech Center (DTC) corporate corridor; South Suburban Parks and Recreation; significant aerospace and defense employer base |
| Broomfield | Broomfield (City & County) | Colorado's only combined city-county; 1stBank Center (major concert and event venue); FlatIron Crossing mall; Flatiron Golf Course; 1UP Broomfield entertainment complex; Oracle, Level 3 Communications, and numerous tech company offices; convenient U.S. 36 corridor location between Denver and Boulder |
| Englewood | Arapahoe | CityCenter Englewood (nationally recognized transit-oriented development replacing a former enclosed mall); Swedish Medical Center; Craig Hospital (world-renowned neurorehabilitation center specializing in spinal cord and traumatic brain injuries); South Broadway antiques and entertainment corridor; Pirates Cove Water Park |
| Highlands Ranch | Douglas (unincorporated) | One of the largest master-planned communities in the US; Highlands Ranch Community Association (one of the largest HOAs in the country); four recreation centers; Eastridge Recreation Center; T-Rex open space trail system; highly ranked Douglas County schools; affluent suburban community south of Denver |
| Littleton | Arapahoe / Jefferson / Douglas | Historic Downtown Littleton (South Broadway antiques district, Breckenridge Brewery flagship, Littleton Museum); Chatfield State Park and Reservoir; South Platte Park; Arapahoe Community College; Hudson Gardens event center; well-preserved small-town downtown character |
| Longmont | Boulder | St. Vrain Valley School District (highly ranked); Oskar Blues Brewery (original home of craft beer canning movement); Longmont Museum; McIntosh Lake; Union Reservoir; Rocky Mountain Beekeepers; growing tech and manufacturing presence in northern Boulder County |
| Castle Rock | Douglas | The Castle Rock (the actual butte formation for which the town is named); Castle Rock Outlet Mall; Philip S. Miller Park; Rock Park trails; significant residential growth as a Denver exurb; Douglas County seat |
| Commerce City | Adams | Dick's Sporting Goods Park (home of the Colorado Rapids MLS soccer club); Rocky Mountain Arsenal National Wildlife Refuge (massive urban wildlife refuge on former chemical weapons site — bison, bald eagles, deer); Suncor Energy oil refinery (largest Colorado Front Range refinery); Adams City High School |
What Time Zone Does the 720 Area Code Use?
Every city in the 720 area code runs on Mountain Time — the same zone as Salt Lake City and Albuquerque. Colorado observes daylight saving time, so clocks shift each March and November:
- Mountain Standard Time (MST): November through mid-March — UTC-7
- Mountain Daylight Time (MDT): mid-March through November — UTC-6
East Coast callers should target 11 a.m.–5 p.m. Eastern to stay within Denver business hours, since 720 runs two to three hours behind Eastern Time depending on the season.
| Caller's Time Zone | Difference from 720 (MT) |
|---|---|
| Eastern (ET) | 720 is 2 hours behind (MDT) / 3 hours behind (MST) |
| Central (CT) | 720 is 1 hour behind (MDT) / 2 hours behind (MST) |
| Pacific (PT) | 720 is 1 hour ahead |
The History of the 720 Area Code
Area code 303 was assigned to all of Colorado in 1947. As cell phones and dial-up internet surged in the 1990s, 970 split off in 1995 to cover rural and western Colorado, leaving 303 to serve the Denver metro alone. Growth soon exhausted 303 too, so regulators added 720 as a full overlay in 1998 rather than splitting the metro again — preserving every existing number. Both codes have served the Denver metro side by side ever since.
Colorado Area Code History Timeline
| Year | Event |
|---|---|
| 1947 | 303 established as the original NANP area code for the entire state of Colorado — all communities statewide used 303 |
| 1995 | 970 split from 303 and assigned to rural and western Colorado — Fort Collins, Greeley, Grand Junction, Durango, Aspen, Vail, Steamboat Springs, and the eastern plains; 303 retained exclusively for the Denver metro and Front Range urban corridor |
| 1998 | 720 approved by the NANP as a full geographic overlay of 303 to address the Denver metro's rapidly depleting 303 number supply, driven by cellular phone and internet dial-up growth throughout the 1990s |
| 1999 | 720 goes into full service as an overlay of 303 for the Denver Metropolitan Area; both 303 and 720 now serve the same geographic territory simultaneously |
| 1999–present | 303 and 720 both actively serve the Denver metro as overlay partners — no geographic split, no distinction between the two area codes by location |
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Why a Local 720 Number Matters for Business
A 720 area code number signals that your business is embedded in the Colorado market, not calling from an unfamiliar out-of-state line. In a region built on tech, aerospace, energy, real estate, healthcare, and tourism, a familiar 720 prefix lifts call answer rates and supplier credibility across the metro. Businesses expanding across the western industrial corridor often compare this reach with our 724 area code guide.
Industries That Benefit Most from a 720 Presence
- Technology and aerospace: The Denver Tech Center and major players like Lockheed Martin Space and Ball Aerospace anchor a fast-growing tech and defense corridor.
- Energy — oil, gas, and renewables: Denver is a headquarters hub for DJ Basin operators and a national leader in wind and solar deployment.
- Real estate and construction: Douglas County, Broomfield, and the U.S. 36 corridor are among the fastest-growing development areas in the country.
- Healthcare and life sciences: The Anschutz Medical Campus in Aurora is one of the largest academic medical campuses in the nation.
- Hospitality and outdoor recreation: Skiing, Red Rocks concerts, and Rocky Mountain National Park draw tens of millions of visitors every year.
How to Get a Virtual Phone Number from CallMama
CallMama is a global virtual phone number platform that lets you claim a real, NANP-registered 720 phone number without a Colorado address, a physical SIM card, or any hardware contract. Plans start at $1.99 per month and include HD voice calling, two-way SMS, voicemail transcription, and call forwarding — everything you need to run a professional Denver metro local presence from any device, anywhere in the world.
- Visit callmama.com or download the CallMama app from the App Store or Google Play — installation is free and takes under two minutes.
- Create a free account using your email address — account verification completes in under sixty seconds.
- Choose a plan that fits your needs — monthly or pay-as-you-go options are available starting at $1.99/month.
- Select your virtual number — choose the United States, enter 720 as the area code, and browse available Colorado numbers.
- Complete payment and activate your 720 number instantly — it goes live as soon as your account is funded.
- Configure call forwarding, voicemail routing, and SMS preferences in your dashboard to match your workflow.
- Start making and receiving calls right away — your 720 phone number works on any smartphone, tablet, or computer immediately.
Scam Calls and the 720 Area Code
The 720 area code is a regular target for caller ID spoofing. Fraudsters display familiar Denver, Aurora, or Boulder numbers because Front Range residents are more likely to answer a recognized local prefix than an unknown out-of-state number. Knowing the common scam patterns helps you protect yourself and your business.
Common Scam Types in the 720 Region
| Scam Type | How It Works | Warning Sign |
|---|---|---|
| IRS tax fraud | Caller threatens immediate arrest or deportation for unpaid federal taxes and demands wire transfer, gift card, or cryptocurrency payment to avoid prosecution | The IRS always contacts you by mail first — they never initiate contact by threatening phone call or demand payment by gift card or wire transfer |
| Social Security Administration fraud | Caller claims your Social Security number has been suspended due to suspicious activity or criminal involvement and demands payment or personal information to resolve the issue immediately | The SSA never suspends Social Security numbers by phone and never demands immediate payment — calls claiming otherwise are always fraudulent |
| Colorado CDLE unemployment fraud | Caller impersonates the Colorado Department of Labor and Employment (CDLE) claiming an overpayment of unemployment benefits and demanding immediate repayment by prepaid card, wire, or Venmo to avoid criminal charges | The Colorado CDLE always sends official written notices by mail — they never demand immediate repayment by phone to a prepaid card or digital payment app |
| Xcel Energy utility shutoff threats | Caller impersonates Xcel Energy (the dominant Colorado Front Range electric and gas utility) demanding same-day payment to avoid immediate power disconnection within the hour | Xcel Energy sends written disconnection notices well in advance — they never demand same-day phone payment to a prepaid debit card or gift card to prevent shutoff |
| Marijuana and dispensary licensing fraud | Caller impersonates the Colorado Marijuana Enforcement Division or a state cannabis licensing official and demands payment of fees or fines to resolve a licensing violation or renewal issue, targeting Colorado dispensary owners and cannabis industry workers | Colorado state agencies never contact licensees by cold call demanding immediate phone payment — all licensing communications come through official written channels and the MED online portal |
How to Protect Yourself
- Verify independently — hang up and call the organization back using a number from their official website, never a number provided by the caller.
- Never share Social Security numbers, bank account details, or business license information with any unsolicited caller.
- Report scam calls to the Federal Trade Commission's FTC fraud report service and to the Colorado Attorney General at coag.gov.
- Register at donotcall.gov to reduce unsolicited telemarketing calls to your 720 number over time.
720 Area Code vs. Neighboring Area Codes
Understanding how 720 relates to surrounding area codes helps you place any Colorado or Rocky Mountain regional call at a glance.
| Area Code | Region | Key Cities |
|---|---|---|
| 720 | Denver Metropolitan Area, Colorado — overlay of 303 | Denver, Aurora, Boulder, Lakewood, Arvada, Westminster, Thornton, Centennial, Broomfield, Englewood, Highlands Ranch, Littleton, Longmont, Castle Rock, Commerce City |
| 303 | Denver Metropolitan Area, Colorado — overlay partner of 720 | Same geographic territory as 720 — Denver, Aurora, Boulder, Lakewood, and all Denver metro communities; 303 was the original Colorado area code established in 1947 |
| 970 | Western and Rural Colorado | Fort Collins, Greeley, Grand Junction, Pueblo (partial), Durango, Aspen, Vail, Steamboat Springs, Glenwood Springs — split from 303 in 1995 for the areas outside the Denver metro |
| 719 | Southeastern Colorado | Colorado Springs, Pueblo, Trinidad, Canon City, La Junta — southeastern Colorado split from 303 in 1988; Colorado Springs is Colorado's second-largest city |
| 307 | Wyoming (entire state) | Cheyenne, Casper, Laramie, Gillette, Rock Springs — Wyoming's sole area code; Cheyenne is approximately 100 miles north of Denver via I-25 |
| 505 | New Mexico (northern and central) | Albuquerque, Santa Fe, Taos — New Mexico's northern area code; Santa Fe is approximately 390 miles south of Denver via I-25 |
Calls from 970 come from Fort Collins or the western slope, and calls from 719 come from Colorado Springs and Pueblo — neither is part of the Front Range metro. A 720 number (or its overlay partner 303) is the exclusive identifier for the Denver Metropolitan Area.
Conclusion
The 720 area code defines the Denver Metropolitan Area, one of the fastest-growing and most livable metros in the country. This guide covered every major city it serves, its Mountain Time Zone, its 1998 overlay history, common scam patterns, and the business case for a local 720 phone number.
Getting started is simple. A virtual 720 number from CallMama activates in minutes — no Colorado address, no hardware, no long-term contract. Activate your virtual Denver metro number today and start building your Front Range presence.
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