Prefix 312-257 — Chicago Zone 01, IL
- Area code
- 312
- Prefix (NXX)
- 257
- Rate center
- Chicago Zone 01
- State
- Illinois
- Time zone
- Central
- Code holder
- CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL
- OCN
- 6333
- Pooled
- Yes (thousands-block pooling)
- Assigned
- 2011-08-18
- LATA
- 358
312-257 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 — 312-257 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 CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL (OCN 6333) as the code holder, assigned August 18, 2011. Because 312-257 participates in thousands-block pooling, individual 1,000-number blocks may belong to other carriers than the code holder.
Neighboring prefixes
| Prefix | Rate center | Code holder |
|---|---|---|
| 312-254 | Chicago Zone 01 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC |
| 312-255 | Chicago Zone 01 | ILLINOIS BELL TEL CO |
| 312-256 | Chicago Zone 01 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC |
| 312-258 | Chicago Zone 01 | ILLINOIS BELL TEL CO |
| 312-259 | Chicago Zone 01 | NEW CINGULAR WIRELESS PCS, LLC - IL |
| 312-260 | Chicago Zone 01 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC |
FAQ
Where is 312-257 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 312-257 numbers?
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 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 312-257 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.