720 Area Code: Location, Cities, Time Zone, Overlay and Phone Number Guide

The 720 area code is a Colorado telephone area code serving the same geographic region as area codes 303 and 983. It primarily covers the Denver metropolitan area and surrounding communities. Area code 720 was introduced in 1998 as an overlay for 303, while 983 was added in 2022 as another overlay. The region uses 10-digit dialing, and 720 phone numbers are in the Mountain Time Zone.

If you received a call from a 720 phone number, are moving to the Denver area, or are considering a local business number, the key point is simple: 720 identifies the Denver-area numbering region, but it does not identify one specific city.

What Is the 720 Area Code?

The 720 area code is a telephone area code in Colorado that serves the Denver-Boulder metropolitan region and shares its geographic territory with 303 and 983.

Unlike an area code that was created by dividing an existing geographic region into separate sections, 720 is an overlay area code. That means multiple area codes can be assigned to telephone numbers in the same geographic area.

Area code 720 was introduced in 1998 as an overlay of 303. Later, area code 983 was added to the same 303/720 territory, with the new code entering service on June 17, 2022. NANPA currently identifies Colorado’s 303/720/983 combination as an overlay complex with 10-digit local dialing.

So, a person living in Denver might have a 303 number, while a neighbor could have a 720 or 983 number. The area code alone does not establish which city the person lives in.

Where Is the 720 Area Code Located?

The 720 area code is located in Colorado, primarily serving the Denver metropolitan region and the surrounding Front Range communities included in the 303/720/983 overlay.

The most recognizable cities and communities associated with this numbering region include:

• Denver
• Aurora
• Boulder
• Lakewood
• Arvada
• Westminster
• Thornton
• Centennial
• Littleton
• Englewood
• Broomfield
• Golden
• Longmont
• Castle Rock
• Highlands Ranch

The important distinction is that 720 is not a city-specific code. The presence of 720 on a phone number indicates that the number belongs to the broader geographic numbering area, not necessarily that the caller currently lives in Denver.

A person’s phone number can also remain associated with its original area code after moving. Therefore, an individual with a 720 number may no longer physically live in the Denver area.

720 Area Code Cities

Because 720 is an overlay rather than a city-exclusive area code, there is no single official list of cities that use only 720.

The broader 303/720/983 numbering territory includes major communities in and around the Denver-Boulder metro area. Denver, Aurora, Boulder, Lakewood, Arvada, Westminster, Thornton, Centennial, Littleton, Englewood, Broomfield, and other nearby communities can have numbers using one of the three overlay codes.

This means two businesses located in the same building could potentially have different area codes.

For example, one business could have a 303 phone number, another could have a 720 phone number, and another could receive a 983 number. Their different area codes do not necessarily indicate different geographic locations.

720 vs. 303 vs. 983

The three area codes are part of the same geographic overlay rather than three separate Denver-area regions.

Feature	303	720	983
State	Colorado	Colorado	Colorado
Introduced	1947	1998	2022
Role	Original area code	Overlay	Additional overlay
Geographic relationship	303/720/983 territory	303/720/983 territory	303/720/983 territory
Local dialing	10 digits	10 digits	10 digits
Time zone	Mountain Time	Mountain Time	Mountain Time

Read More: 720 Area Code

The biggest historical difference is age. 303 is the original code, 720 was introduced later, and 983 is the newest of the three.

Functionally, however, the three codes operate within the same overlay territory. NANPA lists 303, 720, and 983 together as the 303/720/983 overlay complex.

Why Does Denver Have Three Area Codes?

The main reason is the need for additional telephone-numbering capacity.

An area code is combined with a three-digit central-office code and a four-digit subscriber number to create a standard 10-digit telephone number. As demand for numbering resources grows, additional area codes can be introduced. NANPA maintains numbering resources and tracks available and assigned codes across the North American Numbering Plan.

An overlay allows a new area code to be introduced without forcing existing customers to change their established telephone numbers.

That is why 720 did not replace 303, and 983 did not replace either 303 or 720.

When Was the 720 Area Code Created?

The 720 area code was introduced in 1998 as an overlay for the remaining 303 territory in the Denver-Boulder region.

Colorado’s numbering history began with area code 303 covering the entire state. Subsequent geographic splits created additional Colorado area codes, while the Denver-Boulder region eventually received 720 as an overlay.

The next major addition to the same Denver-area numbering region was 983, which was placed into service on June 17, 2022. NANPA’s records identify 983 as an overlay of 303/720.

Colorado Area Code Timeline

Year	Development
1947	303 introduced in Colorado
1988	719 introduced through a geographic split
1995	970 introduced through another geographic split
1998	720 introduced as an overlay of the Denver-Boulder 303 territory
2022	983 introduced as an additional overlay

Read More: 720 Area Code

This timeline explains why a Denver-area phone number can now begin with 303, 720, or 983.

What Time Zone Is the 720 Area Code In?

The 720 area code is in the Mountain Time Zone.

Colorado observes the seasonal change between Mountain Standard Time and Mountain Daylight Time. In practical terms:

• Mountain Standard Time is UTC−7
• Mountain Daylight Time is UTC−6

For people scheduling calls, meetings, appointments, or customer-service hours, the important point is to use Colorado’s local Mountain Time, rather than assuming that an area code automatically reveals a person’s current physical location.

A 720 number can be retained after someone moves elsewhere, so the area code should not be treated as a guaranteed indicator of the caller’s current time zone.

Do You Need 10-Digit Dialing With a 720 Number?

Yes. The 303/720/983 overlay uses 10-digit local dialing.

That means callers generally enter:

Area code + seven-digit phone number

For example:

720-XXX-XXXX

The requirement applies even when the caller and recipient are located in the same local area. NANPA lists the 303/720/983 overlay complex with a 10-digit local dialing plan.

This is particularly important when saving phone numbers in business systems, contact databases, mobile devices, and calling applications.

Using the complete 10-digit number also reduces ambiguity because the same seven-digit local number can exist under different area codes within an overlay.

What Does a 720 Phone Number Mean?

A 720 phone number generally means the number was assigned within the Colorado numbering territory associated with the 303/720/983 overlay.

It does not necessarily mean:

• The owner currently lives in Denver.
• The owner has a physical office in Colorado.
• The caller is currently located in Colorado.
• The number belongs to a particular city.
• The number is a landline rather than a mobile or VoIP number.

Phone numbers can be transferred between carriers and, where permitted, retained when a customer changes service or location.

For that reason, the area code is best understood as a clue about the number’s numbering history and geographic association, not as a precise real-time location.

Can You Get a 720 Phone Number?

Possibly. Whether you can obtain a 720 number depends on the carrier or VoIP provider and the numbering resources available to that provider.

Number availability changes over time. NANPA maintains information about assigned and available central office codes, but consumer-facing availability ultimately depends on the service provider’s inventory and provisioning system.

If you specifically want a 720 number, ask the carrier or VoIP provider whether it currently has a 720 number available in the desired service area.

You may not be able to choose any arbitrary 720 number. A provider can only assign numbers that are available through its numbering resources.

Can Businesses Use a 720 Phone Number?

Yes. A business can use a 720 number for customer calls, sales, support, appointments, marketing, or general business communications.

For a company serving Denver-area customers, a 720 number can communicate an association with the local market. However, the area code itself does not prove that a business has a physical Denver office.

Businesses using VoIP or other hosted phone services should check the provider’s current number availability, calling features, porting rules, messaging support, and pricing before choosing a number.

The area code should be considered part of the overall phone-number setup rather than a substitute for a genuine local business presence.

720 Area Code Overlay Explained

An overlay is a numbering arrangement in which two or more area codes serve the same geographic region.

The 720 area code is therefore not a replacement for 303. Instead, both can be assigned within the same general geographic territory. The later addition of 983 expanded that arrangement to three area codes.

The advantage of an overlay is that existing customers generally do not have to receive a new area code simply because numbering demand has increased.

The trade-off is that callers must use 10-digit dialing within the overlay area. NANPA’s current numbering information confirms the 303/720/983 complex and its 10-digit local dialing plan.

Will 720 Be Replaced?

There is no basis for saying that existing 720 numbers are scheduled to be replaced.

Area code relief planning is handled through the North American Numbering Plan administration process, and future changes depend on numbering-resource demand and regulatory planning. NANPA continues to publish current NPA databases, relief information, and exhaust analyses as numbering conditions change.

It is therefore better not to predict a specific future date for another Denver-area overlay.

If additional numbering relief becomes necessary in the future, the responsible authorities would establish the appropriate plan and implementation schedule.

Is a 720 Number Good for a Denver Business?

A 720 number can be a practical choice for a business that wants a telephone number associated with the Denver-area market.

However, the choice between 303, 720, and 983 is not primarily a technical-performance decision. All three belong to the same overlay territory.

Businesses should instead consider:

• Current number availability
• Customer recognition
• Number portability
• VoIP features
• Calling and texting capabilities
• Business-hours requirements
• Provider pricing
• Existing branding and contact information

A business that already has a recognizable 303 or 720 number may have little reason to change it simply because another overlay code exists.

Frequently Asked Questions