Area code 720: Colorado
Area code 720 is a US state area code for Colorado, on Mountain Time. It has 785 prefixes in service across 12 rate centers, the largest being Denver, Longmont and Fort Lupton. It shares its area with 303 and 983, so local numbers there can start with any of them. Local calls there take 10 digits.
Local time in area code 720
America/Denver
Prefixes in service
785 of 792 possible
12 rate centers
Area code 720 facts
| Location | Colorado, United States |
|---|---|
| Time zone | Mountain Time |
| Overlays | 303, 983 |
| Overlay of | 303 |
| In service since | June 1, 1998 |
| Local calls | 10 digits; toll calls 1 + 10 digits |
| Carrier | Not shown. An area code is where a number was issued; numbers port between carriers. Check line type |
Which cities and towns use area code 720?
NANPA records each prefix against a rate center, the local billing area a number belongs to, usually named after its main town. These are the 720 rate centers with the most prefixes in service.
| Rate center | Prefixes |
|---|---|
| Denver | 678 |
| Longmont | 39 |
| Fort Lupton | 14 |
| Georgetown | 11 |
| Allenspark-Lyons | 10 |
| Deckers | 10 |
| Keenesburg | 9 |
| Hudson | 8 |
| Deer Trail | 3 |
| Strasburg | 1 |
| Byers | 1 |
| Bennett | 1 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 720 number?
NANPA's dialling plan for 720: local calls inside the code take 10 digits, toll calls 1 + 10 digits. From another area code, dial 1 first. From abroad, use +1. The examples use 555-0147, from a range reserved for fictional numbers.
| Local call inside 720 | 720-555-0147 |
|---|---|
| From another US or Canadian area code | 1-720-555-0147 |
| From outside North America | +1 720 555 0147 |
| E.164, for CRMs and SMS tools | +17205550147 |
When did area code 720 start?
Area code 720 went into service on June 1, 1998 as an overlay of 303. Today 720, 303 and 983 cover the same area as an overlay, which is why 10-digit dialling is needed for local calls there.
Tools for 720 numbers
- Area code lookup
Look up any code or a whole list of numbers, or find the codes for a state or city.
- Area code time zone
Local time for a list of numbers, with a callable-now flag.
- NPA-NXX lookup
Rate center and state for one prefix, a level below the area code.
- TCPA calling hours checker
Whether it's inside the federal 8 a.m. to 9 p.m. calling window there now.
Next step
A 720 number tells you where it was issued, not what it is now.
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Area code 720 questions
- What state is area code 720?
- Area code 720 is in Colorado, United States. Its largest rate centers by number of prefixes are Denver, Longmont, Fort Lupton, Georgetown and Allenspark-Lyons.
- What time zone is area code 720 in?
- Mountain Time.
- What area codes overlay 720?
- 303 and 983. An overlay adds a new code to the same area instead of splitting it, so neighbours can have different area codes and local calls need 10 digits.
- When did area code 720 start?
- Area code 720 went into service on June 1, 1998 as an overlay of 303.
- Is a 720 number a cell phone or a landline?
- The area code can't tell you. In the US and Canada mobiles, landlines and VoIP lines share area codes and prefixes, and numbers move between carriers and line types. Only a live line-type lookup answers it for one number.
- How many phone numbers does area code 720 have?
- 785 of its 792 possible prefixes are in service, and each prefix holds up to 10,000 numbers. That counts prefixes assigned to carriers, not numbers in use.
Other area codes in Colorado
Sources
Location, overlays, in-service date and dialling plan: NANPA NPA database, file dated 10/16/2026. Prefixes and rate centers: NANPA central office code assignments, 10/17/2026. Time zones mapped to the IANA time zone database. By the SimpleVerifier Team; how we build these pages.