Area Code 303 Phone Number
for Your Business
Get a local 303 number for your business in Denver, CO. Cloud VoIP with SMS, an auto attendant (IVR), and more — starting at $30/ext/mo. No contracts.
What Is Area Code 303?
Area code 303 is a North American telephone area code serving Denver, Colorado and 1 other city in the region. It is one of the original 1947 North American area codes and operates on Mountain Time. It is part of the 303/720/983 overlay complex. Businesses operating in the 303 area code region use local numbers to build trust with customers, improve answer rates, and establish a professional local presence.
With Zonitel, you can get a new 303 area code number or port your existing one with guided onboarding — no hardware required. Your team can make and receive calls from any device using the Zonitel mobile app or web portal.
Area Code 303 at a Glance
- Region
- Denver / Boulder, Colorado
- In service
- One of the original 1947 North American area codes
- Time zone
- Mountain Time
- Telemarketing hours
- 8 a.m.–9 p.m. Mountain Time for residential numbers (TCPA, 47 CFR 64.1200(c)(1))
Cities Served by Area Code 303
Why Your Business Needs a 303 Local Number
A local number tells customers you're part of the community. People in Denver are more likely to pick up a call from a 303 number they recognize than from an unfamiliar out-of-area number.
Everything Included With Your 303 Number
Zonitel is not just a phone number — it's a complete cloud business phone system. Every plan includes:
Frequently Asked Questions About Area Code 303
What cities use area code 303?
Area code 303 serves the Denver / Boulder area of Colorado. Cities in the 303 region include Denver, CO; Boulder, CO.
Is area code 303 an overlay?
Yes. 303 is part of the 303/720/983 overlay, so new numbers in this region can come from any of those area codes, and local calls require 10-digit dialing.
What time zone is area code 303 in?
Area code 303 is in Mountain Time. Telemarketing calls to residential 303 numbers are limited to 8 a.m.–9 p.m. Mountain Time under the TCPA (47 CFR 64.1200(c)(1)).
Can I get a 303 number for my business without moving there?
Yes. With Zonitel's cloud VoIP, you can get a 303 area code number regardless of where your business is physically located. This lets you establish a local presence in Denver without a physical office.
Can I keep my existing 303 number and switch to Zonitel?
Yes. Number porting is free. Porting commonly takes 5–10 business days depending on your current carrier, and your old service stays active until the coordinated cutover.
How much does a 303 business phone number cost?
Zonitel plans start at $30/extension/month plus tax, with no setup fees and no contracts. Your 303 local number is included in the plan.
Get Your 303 Area Code Number Today
30-day free trial. No annual contract required. Guided onboarding.