business phone · 8 min read
Area Code for Denver
Denver metro uses three area codes: 303 (1947), 720 (1998 overlay), and 983 (2022). Full history, neighborhood map, scam alerts, and how to get a local number.
Denver metro runs on three area codes — 303 (1947 original), 720 (1998 overlay), and 983 (2022 overlay) — making it one of only a handful of US markets with a three-overlay complex on the same geography.
Whether you’re decoding an incoming Colorado number, choosing a local area code for your business, or just curious why the Mile High City needed a third code, this guide covers the full picture: history, neighborhood coverage, the cultural weight of 303, Denver-specific scams, and how to get a business number in minutes.
What’s the area code for Denver?
Denver metro is served by three area codes, all covering the same geography under the North American Numbering Plan (NANP):
| Code | Established | Type | Coverage | Notes |
|---|---|---|---|---|
| 303 | 1947 | Original | Denver metro, Boulder, foothills | One of the original 86 NANP codes; most prestigious |
| 720 | Sep 1, 1998 | Overlay 1 | Same as 303 | Requires 10-digit dialing; no geographic distinction from 303 |
| 983 | Jun 17, 2022 | Overlay 2 | Same as 303/720 | Newest; approved by Colorado Public Utilities Commission; ~23.8M new numbers |
All three codes share the Mountain Time Zone (MT) — UTC−7 in winter, UTC−6 in summer.
A practical rule: if the number starts with 303, it’s an established Denver line — likely a business or long-tenured resident. If it’s 720, it’s Denver post-1998. If it’s 983, it’s a newer assignment from 2022 onward. All three are equally local.
Denver metro area codes by region
Unlike Chicago’s 312/773 downtown-vs-neighborhoods split, Denver’s three codes have no geographic boundary between them. Any of the three can appear in any Denver neighborhood.
Downtown Denver, LoDo, and RiNo
Lower Downtown (LoDo) and the River North Art District (RiNo) are home to Denver’s densest concentration of 303 and 720 numbers. Union Station, Coors Field, and the Arts District on Santa Fe anchor a walkable urban core.
Cherry Creek and Capitol Hill
Cherry Creek’s upscale retail and medical district runs mostly 303. Capitol Hill and the Golden Triangle — Denver’s gallery and studio corridor — follow the same pattern.
Aurora and Lakewood
Aurora (Colorado’s third-largest city) and Lakewood to the west both sit inside the 303/720/983 overlay. Buckley Space Force Base in Aurora adds a significant federal presence to this sub-market.
Westminster, Thornton, and Broomfield
The northern suburbs — Westminster, Thornton, and Broomfield — are fully within the overlay. Broomfield is also home to several tech campuses and is the HQ of Vail Resorts.
Englewood and Centennial
Englewood hosts DISH Network’s headquarters. Centennial, just south, is home to Arrow Electronics (Fortune 200). Both are 303/720/983 territory.
Highlands Ranch and Castle Rock
Douglas County’s fast-growing suburbs — Highlands Ranch and Castle Rock — also fall under the overlay complex, reflecting Denver’s southward expansion along I-25.
Boulder
Boulder sits in the same 303/720/983 overlay despite being its own distinct metro. The University of Colorado, Techstars (founded Boulder 2006), and a dense biotech and aerospace cluster all use 303 or 720 numbers.
History of Denver area codes
Denver’s area code story is a timeline of Colorado’s explosive growth compressed into 75 years.
1947 — 303 is born. AT&T engineers design the North American Numbering Plan and assign area code 303 to the entire state of Colorado. It’s one of the original 86 NPAs. The entire Rocky Mountain region — Denver, Colorado Springs, Grand Junction, Fort Collins — shares a single code.
1988 (March 5) — 719 splits off southeastern Colorado. Population growth and the surge of fax machines strain 303’s number supply. The fix: peel southeastern Colorado away. Area code 719 takes Colorado Springs, Pueblo, and the San Luis Valley. Denver keeps 303.
1995 (April 2) — 970 splits off the rest of Colorado. The remainder of the state — Fort Collins, Greeley, Grand Junction, Vail, Aspen, Steamboat Springs — becomes area code 970. Area code 303 is now confined to the Denver-Boulder region.
1998 (September 1) — 720 overlays 303. Even the reduced 303 territory fills rapidly. The Colorado PUC chooses an overlay — a new code sharing the same geography — over a split that would require number changes. Area code 720 launches. Ten-digit dialing becomes mandatory for all local Denver calls.
2020 — NANPA forecasts exhaustion. The North American Numbering Plan Administrator projects that 303 and 720 will run out of assignable numbers by 2023, driven by Denver’s continued population boom and the proliferation of mobile and VoIP lines.
2021 (May 21) — Colorado PUC approves 983. The Colorado Public Utilities Commission formally authorizes a third overlay for the Denver metro. Area code 983 is selected.
2022 (June 17) — 983 activates. Denver becomes one of the few US markets with a triple overlay — 303, 720, and 983 all ringing in the same neighborhoods simultaneously. The overlay adds roughly 23.8 million numbers, projected to serve the region for approximately 25 more years.
The triple overlay is unusual in the United States. It signals exceptional business density and population growth — a market generating phone numbers at a pace that two codes could not sustain.
Sources: NANPA, Colorado Public Utilities Commission, Wikipedia — Area codes 303, 720, and 983.
303 as Denver and mountain west identity
Area code 303 carries cultural weight that extends well beyond a phone prefix.
“303” is shorthand for Denver itself. Local restaurants, breweries, clothing lines, and event brands use “303” in their names the way New Yorkers use “212.” Denver’s alt-weekly was named 303 Magazine. The number appears in murals across RiNo and LoDo.
Elevation 5,280. Denver’s “Mile High” identity is so strong that the 5,280-foot mark is embedded in the bleachers at Coors Field. 303 and 5280 together form a cultural pair — both shorthand for authentic Denver citizenship.
Sports identity. The Broncos, Nuggets, Avalanche, and Rockies all operate with 303 main lines. The 2023 Nuggets NBA Championship — the franchise’s first — generated a wave of 303-branded celebration merchandise.
Cannabis pioneer. Colorado’s Amendment 64, passed November 2012, made Colorado the first US state to legalize recreational marijuana. Denver was the commercial epicenter. The legal cannabis industry added thousands of new business lines to the 303/720 pool — a unique driver of number demand nationwide.
Craft beer capital. Colorado leads the US in breweries per capita. Coors Brewing (Golden, 303) is the world’s largest single-site brewery. New Belgium Brewing (Fort Collins, 970) and Great Divide Brewing (Denver, 303) built national reputations from Colorado addresses.
Outdoor industry headquarters. VF Corporation (The North Face, Timberland, Vans) relocated its global HQ to Denver in 2019, joining a cluster of outdoor brands that chose Colorado for its proximity to the Rockies and its talent pool.
Tech boom. The Denver Tech Center (DTC) in Greenwood Village emerged in the 1990s as a suburban office cluster. Post-2010, Denver proper absorbed a wave of tech investment — Amazon, Google, and Salesforce all expanded Denver operations. The result: more mobile lines, more VoIP trunks, and faster 303/720 exhaustion.
Denver area code spam and scams
Denver area codes are actively spoofed by scammers exploiting local caller ID trust. Colorado-specific patterns include:
Law enforcement impersonation. FBI Denver has issued formal warnings about callers spoofing 303 and 720 numbers while posing as sheriff’s deputies or federal marshals. The script: a warrant exists for your arrest for missing jury duty, pay immediately by wire or gift card to avoid jail. No legitimate law enforcement agency collects fines by phone.
Utility shutoff threats. Callers impersonating Xcel Energy threaten immediate power shutoff unless payment is made by phone. Xcel never demands instant phone payment — check your account at xcelenergy.com directly if in doubt.
Fake court summons. In a documented Denver incident, nearly 200 people arrived at the Denver City and County Building after receiving fraudulent text messages claiming delinquent fines and including a fake court order image — all carrying spoofed 303-area caller ID.
Marijuana investment fraud. Since Colorado’s legalization, scammers run cannabis “investment opportunity” pitches targeting Colorado residents. The spoofed 303/720 caller ID makes the pitch appear local and credible.
Wildfire recovery scams. After Colorado wildfires (Marshall Fire 2021, East Troublesome 2020), scammers contact affected households using spoofed local numbers, posing as FEMA representatives or contractors.
STIR/SHAKEN and what it means for your business. The FCC mandates that carriers implement STIR/SHAKEN — a caller authentication framework that assigns each outbound call an attestation level. A-attestation means the carrier has fully verified the calling party owns the number. B-attestation is partial. C-attestation is gateway or unverified — typical of spoofed calls.
Despite the mandate, only 44% of carriers were compliant as of 2025, per Colorado reporting. Calls from non-compliant carriers arrive with no authentication signal, triggering “Spam Likely” on modern smartphones.
When you get a Denver number through DialPhone, outbound calls carry A-attestation — the highest trust level — so your business calls reach customers as verified, not screened.
See FCC guidance on spoofing and caller ID and our STIR/SHAKEN glossary entry.
How to get a Denver business phone number
Getting a Denver 303, 720, or 983 number for your business takes under 10 minutes through a cloud VoIP provider. No Colorado office required.
Step 1: Choose your area code. All three Denver codes carry equal local credibility. 303 inventory is older and more limited — check availability first if 303 specifically matters to your brand.
Step 2: Sign up with DialPhone. Search available Denver numbers by area code during signup. Filter by 303, 720, or 983 depending on preference and availability.
Step 3: Assign the number to your team. Route the Denver number to your mobile, desktop app, or a shared team queue. Add a voicemail greeting, call menu, or AI receptionist as needed.
Step 4: Set outbound caller ID. Configure your Denver number as the outbound caller ID so calls you make display the local number — not an 800 number or your personal cell.
Step 5: Port existing numbers if needed. Already have a Denver number with another carrier? Bring it to DialPhone through number porting. US local number ports typically complete in 2–5 business days.
See DialPhone pricing for plan details, or start a free trial to claim your Denver number today.
For the full porting walkthrough, see our number porting guide.
Famous companies in Denver area codes
Denver’s 303/720/983 overlay maps to one of the US mountain west’s most diverse Fortune 500 clusters.
Western Union — Founded 1851; global HQ in Denver, 303. The original American telecommunications company — now a global money transfer and payments network.
DISH Network — HQ Englewood, CO (303/720). One of the largest US satellite TV and wireless providers. Founded 1980; ~14,000 employees.
Arrow Electronics — HQ Centennial, CO (303). Fortune 200 electronics distributor; ~22,000 employees globally.
Newmont Corporation — HQ Denver, 303. World’s largest gold mining company by production; NYSE: NEM.
VF Corporation — HQ Denver, 303. Parent of The North Face, Timberland, Vans, and Dickies. Relocated global HQ from Greensboro, NC to Denver in 2019.
Liberty Media — HQ Englewood, CO (303/720). Owns Formula 1, Atlanta Braves, SiriusXM, and Live Nation.
Re/Max — HQ Denver, 303. One of the world’s largest real estate franchise networks; founded in Denver 1973.
Frontier Airlines — HQ Denver, 303. Ultra-low-cost carrier operating out of Denver International Airport (DEN).
Vail Resorts — HQ Broomfield, CO (303/720). Operates 41 ski resorts across North America, Australia, and Europe; NYSE: MTN.
Colorado’s industry mix — energy, aerospace, healthcare, technology, outdoor retail — means a Denver 303 or 720 number signals multi-sector B2B credibility across a $400B+ state economy.
Denver area code FAQ
Denver area code FAQ
What is the area code for Denver?
Denver uses three area codes under the same overlay complex. Area code 303 is the original, assigned in 1947 when AT&T designed the North American Numbering Plan — it once covered all of Colorado and is the most recognized Denver code.
Area code 720 was added in 1998 as the first overlay when 303 began running low on numbers. Area code 983 launched on June 17, 2022 as the third overlay, approved by the Colorado Public Utilities Commission. All three codes cover the same Denver metro geography — including Aurora, Boulder, Lakewood, Westminster, and Englewood — and all require 10-digit dialing for local calls.
Is 720 a Denver area code?
Yes. Area code 720 is a Denver metro area code introduced on September 1, 1998, as an overlay to area code 303. It covers the same geographic territory as 303 — the entire Denver metro including Aurora, Lakewood, Boulder, Westminster, Englewood, Thornton, and surrounding communities.
Because 720 is an overlay and not a geographic split, a 720 number is just as local as a 303 number. New numbers assigned in the Denver area after 1998 are commonly 720. The code carries no negative connotation — it signals Denver just as clearly as 303.
What is Denver's new area code 983?
Area code 983 is Denver's third area code, activated on June 17, 2022. The North American Numbering Plan Administrator (NANPA) projected that the Denver metro would exhaust its 303 and 720 number supply by 2023. On May 21, 2021, the Colorado Public Utilities Commission approved 983 as an all-services overlay for the existing 303/720 region.
The 983 overlay adds approximately 23.8 million new numbers for a service area of about 3.5 million people. Existing customers kept their numbers unchanged. New lines and second numbers assigned since June 2022 are often 983.
What cities have the 303 area code?
Area code 303 serves the entire Denver metropolitan area. Key cities include Denver (proper), Aurora, Boulder, Lakewood, Englewood, Westminster, Thornton, Littleton, Highlands Ranch, Centennial, Broomfield, Longmont, Castle Rock, Golden, and Greenwood Village.
Boulder also sits in the 303/720/983 overlay complex, even though it has its own distinct cultural identity. Mountain towns along I-70 — including Golden and Idaho Springs — also fall within 303 coverage.
Why does Denver have three area codes?
Denver has three area codes because the metro grew faster than its phone number supply. The 303 code, originally covering all of Colorado, was reduced to just the Denver-Boulder region after 719 split off in 1988 and 970 split off in 1995.
Even the smaller 303 territory filled up quickly due to Denver's tech boom, population growth, and the explosion of mobile and VoIP lines. The Colorado PUC chose overlays — new codes covering the same geography — rather than splits that would force existing customers to change numbers. The result: 303 (1947), 720 (1998), and 983 (2022) all ring in the same Denver neighborhoods.
Are calls from 303 or 720 numbers spam?
Not inherently. Legitimate Denver businesses use 303, 720, and 983 numbers every day. The issue is spoofing — scammers fake a local Denver caller ID to increase answer rates.
FBI Denver and the Colorado Attorney General have warned residents about law enforcement impersonation calls, fake utility shutoff threats, and court summons scams using spoofed 303/720 numbers. STIR/SHAKEN (FCC-mandated caller authentication) assigns each call an attestation level: A (fully verified), B (partial), or C (unverified). Spoofed scam calls typically receive C-attestation and appear as 'Spam Likely.' A Denver number from DialPhone carries A-attestation — the highest trust level.
Can I get a Denver 303 or 720 number without a Denver office?
Yes. Virtual (VoIP) phone numbers are not tied to a physical location. A business anywhere in the US can get a Denver 303, 720, or 983 number through a cloud phone provider and route calls to any device — mobile, desktop app, or team queue.
DialPhone assigns available Denver numbers within minutes. No Denver office, no hardware, no long-term contract required. Outbound calls display your Denver number as caller ID. If you already have a Denver number with another carrier, number porting to DialPhone typically takes 2–5 business days.
What time zone is the 303 area code?
Area codes 303, 720, and 983 are all in the Mountain Time Zone (MT). Mountain Standard Time (MST) is UTC−7, and Mountain Daylight Time (MDT) is UTC−6. Colorado observes daylight saving time, switching on the second Sunday in March and reverting on the first Sunday in November.
For business callers: Denver is 2 hours behind New York (ET), 1 hour behind Chicago (CT), and 1 hour ahead of Los Angeles (PT).
Get a Denver business number
A verified Denver 303, 720, or 983 number builds instant local trust — whether you’re a national company opening the Colorado market or a local business that wants its calls answered rather than screened as spam.
DialPhone provides Denver numbers with STIR/SHAKEN A-attestation, AI receptionist, call recording, and SMS — on a single plan with no hardware required.
Start your free trial → | See all plans →
Related resources:
About the author
Growth Operations Lead at DialPhone
Darshan leads Growth Operations at DialPhone, where he owns three interconnected programs: the comparison content operation, the open VoIP Pricing Dataset, and the test-call methodology used to verify every pricing claim published on the site.
His research process starts with hands-on product trials and live vendor quotes — not marketing pages. Pricing figures are cross-checked against actual invoices and re-verified on a rolling quarterly cycle, with the underlying dataset kept public for independent re-verification. That dataset now covers 40+ VoIP and virtual-number providers across the US and Canada market.
Darshan also leads DialPhone's AI receptionist evaluation program, running structured test-call scenarios across English, Spanish, and French to assess transcription accuracy, intent routing, and escalation behavior. Methodology notes and raw scoring are archived in the research section.
For factual corrections or dataset discrepancies, Darshan can be reached at the DialPhone editorial address. Verified corrections are published as errata with a changelog date — no silent edits.