Prefix 312-481 — Chicago Zone 01, IL

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

Area code
312
Prefix (NXX)
481
Rate center
Chicago Zone 01
State
Illinois
Time zone
Central
Code holder
METROPCS, INC.
OCN
5562
Pooled
Yes (thousands-block pooling)
Assigned
2017-07-07
LATA
358

The 312-481 prefix belongs to area code 312 and is anchored to the Chicago Zone 01 rate center (IL). In NANP terms, the prefix — or NXX — determines the rate center a number is billed against.

Chicago Zone 01 is part of the Chicago-Naperville-Elgin, IL-IN Metropolitan Statistical Area. For routing purposes it sits in LATA 358. Numbers here keep Central time.

The assigned code holder is METROPCS, INC., operating company number 5562, assigned July 7, 2017. 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 312-481 is not proof the call came from Chicago Zone 01: 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 312-481
PrefixRate centerCode holder
312-478 Chicago Zone 01 T-MOBILE USA, INC.
312-479 Chicago Zone 01 TELEPORT COMMUNICATIONS AMERICA, LLC - IL
312-480 Chicago Zone 01 NEW CINGULAR WIRELESS PCS, LLC - IL
312-482 Chicago Zone 01 ILLINOIS BELL TEL CO
312-483 Chicago Zone 01 T-MOBILE USA, INC.
312-484 Chicago Zone 01 SPOK, INC.

FAQ

Where is 312-481 located?

The prefix is assigned to the Chicago Zone 01 rate center in IL, area code 312. It is part of the Chicago-Naperville-Elgin, IL-IN Metropolitan Statistical Area.

Which company owns 312-481 numbers?

METROPCS, INC. 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 312-481 safe to answer?

The prefix itself says nothing about the caller. Legitimate Chicago Zone 01 businesses and spoofed robocalls can both display it. Never share personal data with an unverified inbound caller.