Prefix 303-357 — Denver, CO
A phone number starting 303-357 was issued in the Denver rate center of CO — part of area code 303.
NANPA's central-office code records list MCIMETRO ACCESS TRANSMISSION SERVICES LLC (OCN 7229) as the code holder. Because 303-357 participates in thousands-block pooling, individual 1,000-number blocks may belong to other carriers than the code holder.
A scammer can display 303-357 without ever touching CO. When in doubt, end the call and reach the company or agency through its official website; unwanted robocalls belong in the FTC's fraud report queue.
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.
Neighboring prefixes
| Prefix | Rate center | Code holder |
|---|---|---|
| 303-354 | Denver | TELEPORT COMMUNICATIONS AMERICA, LLC - CO |
| 303-355 | Denver | QWEST CORPORATION |
| 303-356 | Denver | T-MOBILE USA, INC. |
| 303-358 | Denver | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CO |
| 303-359 | Denver | T-MOBILE USA, INC. |
| 303-360 | Denver | QWEST CORPORATION |
FAQ
Where is 303-357 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 303-357 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 303-357 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.