Area code · CO
303 area code
The 303 area code serves Denver, Colorado. Look up a specific 303 number, check spam reports, and stop spam calls automatically.
schedule2 min readUpdated May 15, 2026By the Halo team
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Location
Denver, CO
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Timezone
Mountain
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State
Colorado
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Major cities
Denver, Boulder, Aurora
ABOUTAbout the 303 area code
The 303 area code is assigned to Denver, Colorado. Phone numbers with this area code are used by residents and businesses in the Denver metropolitan area and surrounding communities.
If you've received an unwanted call from a 303 area code number, use the Halo phone lookup tool to check if it has been reported as spam. Halo AI blocks 99% of spam calls at the network level, protecting you from robocalls, scams, and telemarketers before they ever reach your phone.
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