Prefix 312-594 — Chicago Zone 01, IL

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

Area code
312
Prefix (NXX)
594
Rate center
Chicago Zone 01
State
Illinois
Time zone
Central
Code holder
MCIMETRO ACCESS TRANSMISSION SERVICES LLC
OCN
7229
Pooled
Yes (thousands-block pooling)
Assigned
2008-11-06
LATA
358

312-594 identifies a block of numbers in Chicago Zone 01, IL, within the 312 area code. Every US prefix is tied to exactly one rate center; this one is Chicago Zone 01.

The rate center lies in the Chicago-Naperville-Elgin, IL-IN Metropolitan Statistical Area. The serving LATA is 358. Local time follows the Central zone.

Treat the on-screen number as a hint, not evidence — 312-594 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.

NANPA's central-office code records list MCIMETRO ACCESS TRANSMISSION SERVICES LLC (OCN 7229) as the code holder, assigned November 6, 2008. Because 312-594 participates in thousands-block pooling, individual 1,000-number blocks may belong to other carriers than the code holder.

Neighboring prefixes

Prefixes adjacent to 312-594
PrefixRate centerCode holder
312-591 Chicago Zone 01 ILLINOIS BELL TEL CO
312-592 Chicago Zone 01 ILLINOIS BELL TEL CO
312-593 Chicago Zone 01 T-MOBILE USA, INC.
312-595 Chicago Zone 01 ILLINOIS BELL TEL CO
312-596 Chicago Zone 01 TELEPORT COMMUNICATIONS AMERICA, LLC - IL
312-597 Chicago Zone 01 CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL

FAQ

Where is 312-594 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 312-594 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 312-594 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.