Area Code 720

About Area Code 720

Area code 720 is a geographic telephone area code assigned to Denver, Colorado. It operates in the Mountain time zone and was first introduced in 1998. Overlay for 303. Denver metro & front range.

Within Colorado, area code 720 shares numbering capacity with 3 other area codes. The state's 5,839,926-person population (2023 Census Bureau estimate) is served by a combined 4 active codes, with 720 primarily responsible for the Denver region. Colorado's state capital is Denver, and its largest city is Denver.

When you receive a call from a 720 number on your Caller ID, the call originated from a phone number assigned to the 720 area code — but be aware that Local Number Portability (in effect since 2003) means the caller could be physically located anywhere in the US or Canada. Area code 720 only confirms where the number was originally assigned.

Where is the 720 area code located?

Area code 720 is assigned to Denver, Colorado, in the Mountain time zone. The state of Colorado uses 4 active area codes, and 720 is one of them. Calls placed from the 720 area code originate from numbers assigned by NANPA — the North American Numbering Plan Administrator — and the 720 prefix appears on Caller ID for both landline and wireless calls placed from this region.

The Mountain time zone observes Daylight Saving Time, shifting from UTC-7 to UTC-6 in summer. The local time shown above is always current, so you can quickly check whether it's a reasonable hour to call back.

What cities and counties use the 720 area code?

The 720 area code serves 12 notable cities, listed below in order of population. The largest city in the 720 territory is Denver (715,522 residents in Denver County).

• Denver, CO — 715,522 residents (26.1% of 720 numbers)
• Colorado Springs, CO — 486,248 residents (17.7% of 720 numbers)
• Aurora, CO — 399,524 residents (14.6% of 720 numbers)
• Fort Collins, CO — 171,690 residents (6.3% of 720 numbers)
• Lakewood, CO — 156,706 residents (5.7% of 720 numbers)
• Thornton, CO — 142,442 residents (5.2% of 720 numbers)
• Arvada, CO — 123,436 residents (4.5% of 720 numbers)
• Westminster, CO — 115,625 residents (4.2% of 720 numbers)
• Pueblo, CO — 112,121 residents (4.1% of 720 numbers)
• Centennial, CO — 107,201 residents (3.9% of 720 numbers)

Phone number format in area code 720

All phone numbers within area code 720 follow the standard North American 10-digit format:(720) NXX-XXXX. The NXX is the central office prefix (also called an "exchange") and XXXX is the subscriber line number. For long-distance calls within the NANP, dial 1 + 720 + NXX + XXXX. From outside North America, dial your country's international access code, then 1 (the NANP country code), then the 10-digit number.

If you need to verify whether a specific 720 number is wireless, landline, or VoIP, you can use our reverse phone lookup tool. Be aware that number portability means the area code no longer guarantees the caller's physical location — only where the number was first assigned.

History of area code 720

Overlay for 303. Denver metro & front range.

The original 86 area codes were assigned by AT&T and Bell Labs in 1947 as part of the North American Numbering Plan. At the time, rotary-dial phones meant codes with lower digits (like 212 for NYC, 213 for LA, 312 for Chicago) were given to the largest cities because they took less time to dial. Today's area code assignments still reflect those early choices, even though touch-tone and cell phones made the original reason obsolete.

Is the 720 area code safe to answer?

Area code 720 itself is a normal geographic code with no elevated spam risk. That said, scammers can spoof any area code — including 720 — so if you don't recognize the full number, let it go to voicemail and verify the caller's identity before calling back.