Prefix 303-496 — Denver, CO

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

Area code
303
Prefix (NXX)
496
Rate center
Denver
State
Colorado
Time zone
Mountain
Code holder
MCIMETRO ACCESS TRANSMISSION SERVICES LLC
OCN
7229
Pooled
Yes (thousands-block pooling)
Assigned
2004-04-08
LATA
656

The 303-496 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.

The assigned code holder is MCIMETRO ACCESS TRANSMISSION SERVICES LLC, operating company number 7229, assigned April 8, 2004. This is a pooled prefix — expect numbers within it to be split across more than one carrier in 1,000-number blocks.

Caller ID showing 303-496 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 303-496
PrefixRate centerCode holder
303-493 Denver LEVEL 3 COMMUNICATIONS, LLC - CO
303-494 Denver QWEST CORPORATION
303-495 Denver MCIMETRO ACCESS TRANSMISSION SERVICES LLC
303-497 Denver QWEST CORPORATION
303-498 Denver COMCAST IP PHONE, LLC
303-499 Denver QWEST CORPORATION

FAQ

Where is 303-496 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 303-496 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 303-496 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.