Area code 303
Area code 303 serves Denver and nearby parts of Colorado, including Boulder, Aurora and Centennial. It is on Mountain Time, which observes daylight saving time. 720 and 983 are overlays for the same area.
Area code 303 at a glance
Cities in 303
- Denver
- Boulder
- Aurora
- Centennial
An area code shows where a number was first assigned. Mobile numbers keep their area code when people move, so the person you’re calling may be somewhere else.
When you can call a 303 number
Federal telemarketing rules under the TCPA allow sales calls between 8 AM and 9 PM in the called person’s local time. Here is that window for a 303 number, shown in your own time zone.
General information, not legal advice. Some states add rules for Sundays, holidays or the number of calls. See our calling hours guide.
| If you’re on | You can call 303 between |
|---|---|
| Eastern | 10:00 AM to 11:00 PM |
| Central | 9:00 AM to 10:00 PM |
| Mountain | 8:00 AM to 9:00 PM |
| Arizona | 7:00 AM to 8:00 PM |
| Pacific | 7:00 AM to 8:00 PM |
See the time in 303 without leaving your CRM
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Other area codes in Colorado
Questions about 303
What time zone is area code 303?
Area code 303 is on Mountain Time. It observes daylight saving time.
Where is area code 303?
Area code 303 is in Colorado. Its main city is Denver, and it also covers Boulder, Aurora and Centennial.
What are the legal hours to call a 303 number?
Under the federal TCPA, sales calls are allowed from 8 AM to 9 PM in the called person’s local time. Personal and informational calls are not limited by these hours.
What area codes overlay 303?
720 and 983 cover the same area as 303, so numbers in the same town can have either code.