Prefix 312-500 — Chicago Zone 01, IL

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

Area code
312
Prefix (NXX)
500
Rate center
Chicago Zone 01
State
Illinois
Time zone
Central
Code holder
ONVOY, LLC
OCN
224C
Pooled
Yes (thousands-block pooling)
Assigned
2018-05-22
LATA
358

A phone number starting 312-500 was issued in the Chicago Zone 01 rate center of IL — part of area code 312.

NANPA's central-office code records list ONVOY, LLC (OCN 224C) as the code holder, assigned May 22, 2018. Because 312-500 participates in thousands-block pooling, individual 1,000-number blocks may belong to other carriers than the code holder.

A scammer can display 312-500 without ever touching IL. 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.

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.

Neighboring prefixes

Prefixes adjacent to 312-500
PrefixRate centerCode holder
312-497 Chicago Zone 01 CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL
312-498 Chicago Zone 01 T-MOBILE USA, INC.
312-499 Chicago Zone 01 ILLINOIS BELL TEL CO
312-501 La Grange CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL
312-502 Chicago Zone 01 CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL
312-503 Chicago Zone 01 TELEPORT COMMUNICATIONS AMERICA, LLC - IL

FAQ

Where is 312-500 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 312-500 numbers?

ONVOY, 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 312-500 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.