The 303 Area Code Explained — Colorado Phone Numbers

Area code 303 covers Denver and surrounding areas in Colorado. It is one of the original 86 area codes established by AT&T in 1947. Today it shares its territory with overlay codes 720 and 983. For the full picture, see all Colorado area codes.

History of Area Code 303

Area code 303 is one of the 86 original area codes created by AT&T in 1947, when the first nationwide numbering plan went into effect on January 1 of that year. It was assigned to Colorado as part of the initial map that divided the United States and Canada into geographic dialing regions.

Since its activation, the geographic area covered by 303 has been reshaped by the following splits:

• 1988 — area code 719 split off to cover southeastern Colorado — Colorado Springs, Pueblo, and the southern half of the state — on March 5, 1988
• 1995 — area code 970 split off to cover the northern, western, and eastern portions of Colorado outside the Denver metro — Fort Collins, Grand Junction, Vail, Aspen — on April 2, 1995

Overlay codes have been added to the same geographic territory in:

• 1998 — area code 720 activated as an overlay
• 2022 — area code 983 activated as an overlay

Cities and Areas Served by 303

Area code 303 serves the Denver metropolitan area and the central Front Range, including the following cities and communities:

• Denver
• Boulder
• Aurora
• Lakewood
• Arvada
• Westminster
• Thornton
• Centennial
• Littleton
• Englewood
• Wheat Ridge
• Brighton
• Broomfield

Nearby area codes covering the same broader region include: 720, 983, 719, 970, 748.

Overlay Codes for 303

Area code 720 shares the same geographic territory as 303 (added in 1998). New phone numbers in the region may be assigned either code.

Area code 983 shares the same geographic territory as 303 (added in 2022). New phone numbers in the region may be assigned either code.

Because multiple area codes serve the same area, ten-digit dialing is mandatory for all local calls. A call from any of these codes originates from the same geographic region in Colorado.

The Cultural Weight of a 303 Number

Area code 303 was one of the original 86 area codes assigned in October 1947, covering the entire state of Colorado. The configuration held for 41 years — Colorado was sparsely populated relative to most other states with single-NPA assignments, and demand for additional numbers didn’t reach critical levels until the late 1980s. On March 5, 1988 the first split moved southeastern Colorado (Colorado Springs, Pueblo, and the southern half of the state) into the new 719 area code. Seven years later, on April 2, 1995, the second split moved the northern, western, and eastern portions of Colorado (Fort Collins, Grand Junction, Vail, Aspen) into 970, leaving 303 covering only the Denver metropolitan area and the central Front Range. Three years after that, on June 1, 1998, area code 720 was added as the first overlay — Colorado’s earliest overlay implementation — and ten-digit dialing became mandatory across the Denver metro for the first time.

303 has accumulated unusual cultural weight for an area code of its size. Colorado celebrates an unofficial ‘303 Day’ (March 3 — March being the third month) as a regional identity marker, with branded merchandise sold by Denver businesses and a long-running tradition of local restaurants offering 303-themed promotions. The prefix appears in Denver hip-hop, in the branding of local breweries and dispensaries (Colorado’s cannabis industry, legalized in 2012, has consistently embraced the code), and in marketing for the region’s outdoor and lifestyle brands. A second overlay, 983, activated on June 17, 2022, addressing the continued exhaustion pressure caused by the Front Range’s rapid population growth — Colorado’s population grew by approximately 14.8 percent between 2010 and 2020, one of the fastest growth rates in the country. The three-code 303/720/983 complex now serves roughly 3.2 million residents in the Denver metro area.

How to Get a Phone Number with Area Code 303

There are three ways to get a phone number with the 303 area code, each suited to a different need:

1. Buy from a premium-number specialist. Companies that hold curated inventories of specific area codes can sell you a 303 number directly, often with a one-time fee and ownership transferred to you (no recurring carrier fees). This is the option for picking a specific memorable number, or for getting an area code that most carriers won’t let you request. Browse our 303 inventory.
2. Sign up with a VoIP carrier. Voice-over-IP services (such as Google Voice, OpenPhone, Grasshopper, and many others) can typically provision a 303 number on request, especially for active overlay codes. You won’t usually get to pick the specific number, but you’ll get a working line in the area code. This is the cheapest option for anyone who doesn’t need a particular number.
3. Port an existing 303 number. If you already have a 303 phone number with another carrier, you can transfer it (port it) to a new service provider while keeping the number. This works for landlines, cell phones, and VoIP services, though landlines outside of Colorado sometimes can’t accept inbound ports of 303 numbers due to 911 routing rules.

Looking for a 303 number? 212areacode.com offers premium 303 numbers for Denver, Colorado — choose your number, port it to any carrier in 3–5 business days, and pay a one-time fee with no monthly charges. Browse available 303 numbers →

Frequently Asked Questions

Is the 303 area code still in use?
Yes. 303 is actively assigned to new phone lines in the Denver metropolitan area and the central Front Range.

What is the difference between 303 and 720?
Today they share the same geographic territory in Colorado. New phone lines in the area may be assigned either code. The two codes work identically for calling, billing, and service.

Can I get a 303 number if I don't live in Colorado?
Yes. Phone numbers are no longer tied to a physical address. With VoIP service or a number broker, you can hold a 303 number from anywhere in the world. The number routes to whatever device or carrier you specify.

Is 303 a scam area code?
No. 303 is a legitimate, active area code for the Denver metropolitan area and the central Front Range. Like any area code, scammers occasionally spoof 303 caller IDs, but the code itself is heavily used by real Colorado businesses, government offices, and residents.

What is '303 Day'?
303 Day is an unofficial Colorado holiday celebrated on March 3 (the third day of the third month) that has emerged as a regional identity marker. Local businesses offer 303-themed promotions and merchandise, and the day functions as a casual expression of Denver-and-Front-Range pride.

What's the difference between 303, 720, and 983?
All three serve the same geographic territory — the Denver metropolitan area and the central Front Range. The difference is vintage: 303 dates to 1947, 720 to 1998, and 983 to 2022. New phone lines may be assigned from any of the three codes.

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• Who Invented Area Codes?
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