What time zone is area code 303 in?

Area code 303 uses Mountain Time.

What area codes overlay 303?

720 and 983 serve the same area as 303. New numbers in the area can get any of these codes, which is why local calls need all 10 digits.

Is a call from area code 303 a scam?

The area code alone doesn’t tell you. Most calls from 303 are ordinary local calls, but scammers can fake (“spoof”) any number. If you don’t recognize a 303 number, let it go to voicemail.

Can a 303 number be outside Colorado?

Yes. People keep their numbers when they move and when they switch to mobile or internet phone services, so a 303 caller can be anywhere.

Area code 303

Where is area code 303?

Denver, Aurora and Littleton, Colorado

Local time: … (Mountain Time)

State	Colorado
Country	United States
Main cities	Denver, Aurora and Littleton
Time zone	Mountain Time
Overlay area codes	720 and 983
In service since	1947
Assigned prefixes	784
Dialing format	(303) XXX-XXXX · +1 303 XXX XXXX from abroad

Look up a 303 number

Cities and towns in area code 303

Listed by how many phone prefixes (the 3 digits after the area code) are assigned to each place in 303.

Denver, CO (618)
Aurora, CO (23)
Littleton, CO (17)
Longmont, CO (17)
Boulder, CO (16)
Fort Lupton, CO (11)
Golden, CO (10)
Broomfield, CO (8)
Englewood, CO (6)
Lakewood, CO (6)
Brighton, CO (5)
Deckers, CO (5)
Highlands Ranch, CO (5)
Castle Rock, CO (4)
Evergreen, CO (3)
Keenesburg, CO (3)
Parker, CO (3)
Deer Trail, CO (2)
Georgetown, CO (2)
Hudson, CO (2)
Lyons, CO (2)
Arvada, CO (1)
Bennett, CO (1)
Black Hawk, CO (1)
Byers, CO (1)
Elbert, CO (1)
Elizabeth, CO (1)
Erie, CO (1)
Idaho Springs, CO (1)
Kiowa, CO (1)
Larkspur, CO (1)
Louisville, CO (1)
Morrison, CO (1)
Nederland, CO (1)
Niwot, CO (1)
Roggen, CO (1)
Strasburg, CO (1)

Phone companies in area code 303

The carriers that hold the most 303 prefixes. People can move their number to another carrier, so this shows who first issued a number, not who serves it today.

Prefixes	Carrier
448	Qwest (Lumen)
60	Verizon Wireless
58	Level 3 Communications
39	T-Mobile USA
35	New Cingular Wireless PCS (AT&T)
31	Spok
31	Mcimetro Access Transmission Services
28	Teleport Communications America

All 784 prefixes in area code 303

Pick the 3 digits after the area code to see that prefix’s city and carrier.

Area codes that overlay 303

Questions

Where is area code 303?: Area code 303 is in Colorado. It serves Denver, Aurora, Littleton, Longmont and Boulder and 32 other cities and towns.
What time zone is area code 303 in?: Area code 303 uses Mountain Time.
What area codes overlay 303?: 720 and 983 serve the same area as 303. New numbers in the area can get any of these codes, which is why local calls need all 10 digits.
Is a call from area code 303 a scam?: The area code alone doesn’t tell you. Most calls from 303 are ordinary local calls, but scammers can fake (“spoof”) any number. If you don’t recognize a 303 number, let it go to voicemail.
When did area code 303 start?: 303 went into service in 1947.
Can a 303 number be outside Colorado?: Yes. People keep their numbers when they move and when they switch to mobile or internet phone services, so a 303 caller can be anywhere.

Other area codes in Colorado

Area code	Main cities
719	Colorado Springs, Pueblo and Cañon City
748	Durango, Eagle and Estes Park
970	Fort Collins, Greeley and Grand Junction