Prefix 303-481 — Denver, CO

NANPA CO code assignment, current as of July 28, 2026.

Area code
303
Prefix (NXX)
481
Rate center
Denver
State
Colorado
Time zone
Mountain
Code holder
MCIMETRO ACCESS TRANSMISSION SERVICES LLC
OCN
7229
Pooled
Yes (thousands-block pooling)
LATA
656

The 303-481 prefix belongs to area code 303 and is anchored to the Denver rate center (CO). In NANP terms, the prefix — or NXX — determines the rate center a number is billed against.

Denver is part of the Denver-Aurora-Centennial, CO Metropolitan Statistical Area. For routing purposes it sits in LATA 656. Numbers here keep Mountain time.

Code-holder of record: MCIMETRO ACCESS TRANSMISSION SERVICES LLC (OCN 7229). The prefix is pooled: its ten thousands-blocks can be shared among several carriers, so different 303-481 numbers may be served by different companies.

Caller ID showing 303-481 is not proof the call came from Denver: spoofing and porting both detach numbers from their origin. To verify a caller, hang up and dial the organization's published number, and report suspicious calls to the FTC.

Neighboring prefixes

Prefixes adjacent to 303-481
PrefixRate centerCode holder
303-478 Denver NEW CINGULAR WIRELESS PCS, LLC
303-479 Denver TELEPORT COMMUNICATIONS AMERICA, LLC - CO
303-480 Denver QWEST CORPORATION
303-482 Denver LEVEL 3 COMMUNICATIONS, LLC - CO
303-483 Denver LEVEL 3 COMMUNICATIONS, LLC - CO
303-484 Denver TELEPORT COMMUNICATIONS AMERICA, LLC - CO

FAQ

Where is 303-481 located?

The prefix is assigned to the Denver rate center in CO, area code 303. It is part of the Denver-Aurora-Centennial, CO Metropolitan Statistical Area.

Which company owns 303-481 numbers?

MCIMETRO ACCESS TRANSMISSION SERVICES LLC holds the code, but the prefix is pooled — individual thousands-blocks can be assigned to other carriers, and numbers may be ported to any provider.

Is a call from 303-481 safe to answer?

The prefix itself says nothing about the caller. Legitimate Denver businesses and spoofed robocalls can both display it. Never share personal data with an unverified inbound caller.