303 Area Code — Scam Calls, Location & Who's Calling

Area code 303 serves Colorado in the Mountain time zone, in service since 1947. The FCC has 6,620 unwanted-call complaints against 5,356 different 303 numbers on record. Look up the exact number that called you below.

Most-reported 303 numbers

Ranked by FCC unwanted-call complaints. Click a number for its full report.

303 unwanted-call complaints, last 12 months

Monthly FCC complaint volume against 303 numbers. Spikes usually mark an active robocall campaign cycling through the code.

Carriers operating in 303

Carriers assigned to 303 prefixes that visitors have looked up so far — resolved from official NPA-NXX assignment records.

QWEST CORPORATIONI · 52 prefixes
LEVEL 3 COMMUNICATIONS, LLC - COC · 21 prefixes
MCIMETRO ACCESS TRANSMISSION SERVICES LLCC · 12 prefixes
TELEPORT COMMUNICATIONS AMERICA, LLC - COC · 9 prefixes
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - COWireless · 7 prefixes
T-MOBILE USA, INC.Wireless · 6 prefixes
ONVOY, LLC - COC · 5 prefixes
COMCAST IP PHONE, LLCC · 5 prefixes

About area code 303

Serves: Colorado
Time zone: Mountain
In service since: 1947-01-01
Overlay: Yes — 10-digit dialing

Source: NANPA numbering records, refreshed weekly.

Spam calls from 303? What to know

Seeing repeated missed calls from 303 numbers you don't recognize is the classic signature of neighbor-spoofing robocall campaigns. The caller isn't necessarily in Colorado — spoofing software displays whatever digits the campaign chooses. Never call unknown numbers back; look them up first, and report unwanted calls to the FCC to build the public record.

Area code 303 FAQs

Where is area code 303?

Area code 303 serves Colorado, in the Mountain time zone. It is part of an overlay complex, so multiple area codes serve the same territory and 10-digit dialing is required. It has been in service since 1947.

Why do I keep getting calls from 303 numbers?

Robocallers use "neighbor spoofing" — displaying a number with a local area code to make you more likely to answer. A call showing area code 303 may not originate from Colorado at all. Look up the full 10-digit number on this site to see its complaint history before calling back.

Are 303 numbers safe to call back?

Area codes themselves are neither safe nor unsafe — 303 contains millions of legitimate lines alongside any spoofed or spam numbers. The FCC has logged 6,620 unwanted-call complaints against 5,356 distinct 303 numbers in our current data window. Check the specific number's report page before returning a missed call.