Phone number reference · United States
303 area code
Denver, Boulder and surrounding Front Range communities.
303 is associated with the Denver-Boulder region and surrounding Front Range communities. It shares an overlay arrangement with 720 and 983. Colorado extends well beyond this area, so a 303 label should not be used as a statewide service-area promise.
Denver and the Front Range
Geographic code · In service
303 at a glance
- Region
- Denver and the Front Range
- Time zone
- Mountain Time
- In service since
- 01-Jan-1947
- Overlay arrangement
- 303/720/983
Numbering details checked September 21, 2026 against the NANPA database. See the official area-code maps for boundaries.
Questions about 303
What do 720 and 983 have to do with 303?
720 and 983 are overlays in the 303 region. Customers can have any of these prefixes without living in a different metropolitan market.
Is a 303 call safe to answer?
The 303 prefix identifies a numbering region, not a caller's identity or trustworthiness. Verify an unexpected request by contacting the organization through a number you already know.
Can I get a 303 business number?
Search the available numbers in VeraDial. Inventory changes, so a 303 number is not guaranteed. You can also keep your current carrier number and forward voice calls to a VeraDial line; existing texts stay with your carrier.
Related area-code guides
Explore overlays, nearby regions and other business markets.
Browse all 40 area-code guides