Prefix 303-303 — Denver, CO
303-303 identifies a block of numbers in Denver, CO, within the 303 area code. Every US prefix is tied to exactly one rate center; this one is Denver.
The rate center lies in the Denver-Aurora-Centennial, CO Metropolitan Statistical Area. The serving LATA is 656. Local time follows the Mountain zone.
Treat the on-screen number as a hint, not evidence — 303-303 can be spoofed like any US prefix. If a call feels off, verify through an official callback number and file a complaint with the FCC or FTC.
The assigned code holder is HD CARRIER LLC, operating company number 321J, assigned August 26, 2024. This is a pooled prefix — expect numbers within it to be split across more than one carrier in 1,000-number blocks.
Neighboring prefixes
| Prefix | Rate center | Code holder |
|---|---|---|
| 303-300 | Denver | QWEST CORPORATION |
| 303-301 | Denver | LEVEL 3 COMMUNICATIONS, LLC - CO |
| 303-302 | Denver | MCIMETRO ACCESS TRANSMISSION SERVICES LLC |
| 303-304 | Fort Lupton | NEW CINGULAR WIRELESS PCS, LLC |
| 303-305 | Denver | MCIMETRO ACCESS TRANSMISSION SERVICES LLC |
| 303-306 | Denver | QWEST CORPORATION |
FAQ
Where is 303-303 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 303-303 numbers?
HD CARRIER 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 303-303 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.