WHAT YOU NEED TO KNOW
Area code 720 serves the Denver metro area in Colorado, covering cities including Denver, Aurora, Lakewood, and Arvada. Established in March 1998 as an overlay of area code 303, the code covers approximately 3.0 million residents and operates alongside 303 as a primary local code for the entire Denver metropolitan region.
- Population: ~3.0 million residents in the metro
- Overlay: Overlay: 303
- Dialing: 10-digit dialing required
- Source Type: Local geographic code
Geographic Coverage
Area code 720 covers the entire Denver metro area, spanning multiple counties including Denver, Arapahoe, Jefferson, Adams, Douglas, and Broomfield. Major cities within the code include Denver, Aurora, Lakewood, Arvada, Westminster, Thornton, Centennial, Highlands Ranch, Littleton, Englewood, Commerce City, Parker, Castle Rock, Brighton, and Golden. Because 720 is a full overlay of 303, both codes apply to the same geographic footprint across the Front Range.
Population and Business Context
The Denver metro is one of the fastest-growing markets in the United States, with a population of roughly 3.0 million residents. Key industries include aerospace and defense, telecommunications, energy, healthcare, and technology. The region hosts major employers such as Lockheed Martin, Centura Health, and a growing number of tech startups. Denver's economy has diversified significantly over the past two decades, making the 720 area code a high-volume market for both consumer and business telephony.
Area Code History
Area code 303 was one of the original NANP codes assigned in 1947 and originally covered all of Colorado. As the state's population grew, 719 was split off in 1995 to serve southern and southeastern Colorado. By 1998, demand for numbers in the Denver metro had exhausted much of the 303 supply, prompting regulators to introduce 720 as a full geographic overlay rather than a split, meaning both codes serve the same territory.
How to Dial
Because 720 and 303 overlay the same area, 10-digit dialing is required for all local calls within the Denver metro. Callers must dial all 10 digits, including the area code, even when calling a neighbor. Long-distance calls to numbers outside the metro still require dialing 1 before the 10-digit number. This rule applies to both landlines and mobile phones registered in the 720 or 303 service area.
Need a 720 Number for Your Denver Business?
Businesses operating in the Denver metro can provision a 720 local tracking number through Convirza. Whether you run a single-location shop in Lakewood or manage multiple service areas across the Front Range, a local 720 number reinforces regional presence and lets you track exactly which campaigns drive inbound calls. With Convirza, every call to your 720 number is automatically scored, recorded, and source-attributed using dynamic number insertion (DNI). Calls route to any team member, location, or call center you designate. You get a complete picture of call volume, lead quality, and marketing ROI - without manual tracking or guesswork.
750+ customers · 25 years of call data