Prefix 312-679 — Chicago Zone 01, IL
- Area code
- 312
- Prefix (NXX)
- 679
- Rate center
- Chicago Zone 01
- State
- Illinois
- Time zone
- Central
- Code holder
- U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS
- OCN
- 671J
- Pooled
- Yes (thousands-block pooling)
- Assigned
- 2026-01-29
- LATA
- 358
312-679 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 — 312-679 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.
Code-holder of record: U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS (OCN 671J), assigned January 29, 2026. The prefix is pooled: its ten thousands-blocks can be shared among several carriers, so different 312-679 numbers may be served by different companies.
Neighboring prefixes
| Prefix | Rate center | Code holder |
|---|---|---|
| 312-676 | Chicago Zone 01 | FIRST COMMUNICATIONS, LLC |
| 312-677 | Chicago Zone 01 | SPOK, INC. |
| 312-678 | Chicago Zone 01 | T-MOBILE USA, INC. |
| 312-680 | Chicago Zone 01 | ONVOY, LLC |
| 312-681 | Chicago Zone 01 | ILLINOIS BELL TEL CO |
| 312-682 | Chicago Zone 01 | NUSO, LLC |
FAQ
Where is 312-679 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 312-679 numbers?
U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 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 312-679 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.