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Denver Metro

Area Code `303`: Denver, CO Local Numbers

Area code 303 is the original telephone area code for Denver, Colorado. Established in 1947 as one of the first North American Numbering Plan codes, 303 is the heritage code of the Denver metro — strongly associated with the city's tech industry, mountain lifestyle, and Mile High identity.

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303 Quick Facts

Live data

📍

Region

Denver, CO

🕐

Time Zone

Mountain (MT)

🗺️

Major Cities

Denver, Aurora, Lakewood

📞

Overlay For

Area Code 720

✅

Numbers Available

24 numbers available

Area Codes

Denver Metro

Area Code `303`: Denver, CO Local Numbers

Set Up AI Calling for 303 — 2 Min

See how AI calling works →

1,134+ Denver businesses already use Brilo

303 Quick Facts

Live data

📍

Region

Denver, CO

🕐

Time Zone

Mountain (MT)

🗺️

Major Cities

Denver, Aurora, Lakewood

📞

Overlay For

Area Code 720

✅

Numbers Available

24 numbers available

Area Code

Feature Answer

What is Area Code 303?

Area code 303 is a North American telephone area code assigned to Denver, Colorado. First assigned in 1947 as one of the original 86 area codes in the North American Numbering Plan, 303 is among the oldest area codes in the country. It serves the Denver metro — including Denver, Aurora, Lakewood, Boulder, Westminster, and Arvada — and is a local (non-toll-free) area code in the Mountain Time Zone.

303 originally covered all of Colorado. As the state grew, 1988's 719 split carved out southern Colorado, and 1995's 970 split removed the western slope and northern plains, leaving 303 with just the Front Range from Denver to Boulder. Continued growth led to overlay 720 in 1998, and a third overlay 983 was added in 2024. Despite the multiple overlays, a 303 number remains the heritage signal for established Denver tech, energy, and outdoor industry companies.

📍

Denver, CO

⏰

Mountain (MT)

✅

24 numbers available

📅

Est. 1947

Area Code

Coverage Data

Cities & Zip Codes in Area Code 303

All cities and communities served by the 303 area code across the Denver metro and Front Range.

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303 Area Code City Coverage

1,134+

City

County

Zip Codes

Est. Businesses

Aurora

Arapahoe

80010 – 80019

~9,200

Set up 303 AI calling →

Centennial

Arapahoe

80111 – 80122

~4,400

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Denver

80201 – 80239

~32,500

Set up 303 AI calling →

Englewood

Arapahoe

80110 – 80113

~2,900

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Lakewood

Jefferson

80214 – 80232

~5,800

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Wheat Ridge

Jefferson

80033 – 80034

~1,700

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Area Code

Spam Inteligence

Is Area Code 303 Spam?

We aggregate spam reports from thousands of sources. Here's what the data shows for 303 this month.

303 Spam Activity Score — Last 30 Days

Low

25% of reported US area codes have higher spam activity

📊 Total reports this month

102

📞 Top reported prefixes

303-447, 303-619

📈 Trend vs last month

↓ 9% lower

🏆 Trust ranking

Top 25% of US area codes

ANSWER RATES, EXPLAINED

Why do 303 customers screen unknown calls?

Spam filters don't distinguish between scam calls and unknown legitimate ones — they both get screened. Denver customers pick up a verified 303 line 3.3x more often than an unverified one because the caller ID looks like a real business.

3.3x more pickups on a verified 303 line

Your 303 line, but with the caller-ID problem solved. Brilo bundles verification, AI agents, and live transcripts so customers see a real business name.

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Area Code

Why Go local

Why Denver Businesses Choose a 303 Number

More than 1,134 Denver companies route their calls through Brilo's AI agents on a 303 line. Mile-high businesses keep the area code locals trust — and let AI handle the volume.

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Local vs Other Number Types

📍 Local Number

81% answer rate

📞 Toll-Free 800 Number

33% answer rate

📱 Out-of-State Number

19% answer rate

❓ Unknown / VoIP

10% answer rate

📍

Local Trust Signal

Denver customers pick up a 303 call 3.9x more often than one from out-of-state. The Mile High City's original code still earns more callbacks than any 800 number ever could.

🤖

AI-Powered Calls

Brilo's AI agents work your 303 line 24/7 — inbound calls answered, outbound dials made, every word transcribed live. Built for Denver teams that want coverage without adding staff.

⚡

Setup in 2 Minutes

Pick a 303 number, configure your agent with a few prompts, and ship inside two minutes. Salesforce, HubSpot, and 6,000+ other tools your Denver stack already uses wire right in.

Brilo 2.0

303 FAQs

What Mile-High businesses want to know about 303 numbers.

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Who uses area code 303?

Is 303 a toll-free number?

Can I get a 303 number if my business isn't in Colorado?

What area code is 303 from?

Is a 303 number associated with spam?

How do I set up a 303 number with AI calling?

What is the difference between 303 and 720?

Do I need to dial the area code for local calls within 303?

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Join Discord

Connect with our community, ask questions, and stay updated on product news.

Book a Call

Schedule a quick call with our team to explore solutions for your needs.

Join Discord

Connect with our community, ask questions, and stay updated on product news.

Book a Call

Schedule a quick call with our team to explore solutions for your needs.

Area Code 303: Denver, CO Local Numbers

Area Code 303: Denver, CO Local Numbers

Never Miss a Customer Call Again. Let AI Close the Loop—24/7.

Never Miss a Customer Call Again. Let AI Close the Loop—24/7.

Never Miss a Customer Call Again. Let AI Close the Loop—24/7.

Never Miss a Customer Call Again. Let AI Close the Loop—24/7.

Area Code `303`: Denver, CO Local Numbers

Area Code `303`: Denver, CO Local Numbers