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AREA CODE · ILLINOIS

Area code 312

Area code 312 covers Chicago, Illinois. Map, time zone, overlays, carriers, the full list of prefixes and how to dial it.

State: Illinois Major City: Chicago Central Time (CT) Overlay: 312/872
01 / WHERE IT IS

Where is area code 312?

Area code 312 is assigned to Chicago and the surrounding region in Illinois. Calls to numbers that start with 312 are routed to this area.

Area code 312 shares its territory with 872. Because it is an overlay, local calls require dialing all 10 digits.

Counties covered

Cook County

Line types

  • Mobile 31.76%
  • Landline 68.24%
02 / MAP

Area code 312 on the map

The shaded area joins the code’s numbering centers; the marker shows its main city.

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© OpenStreetMap contributors

03 / LOCAL TIME

Current time in Chicago

This area code is in the Central Time (CT) time zone.

Local timeChicago, IL--:--:--

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America/ChicagoLive
04 / HOW TO DIAL

How to call Chicago

WITHIN THE US312 XXX XXXX

Always 10 digits — landline, mobile or VoIP. Local, long distance or a different state: the format is always the same. You do not need to dial the 1 first.

FROM ABROAD+1 312 XXX XXXX

Exit codes: 00 Europe/Mexico · 011 Canada · 010 Japan · + universal

WHATSAPP / IMESSAGE+1 312 XXX XXXX

Always save the number in international format so messaging apps recognize it correctly:

Call typeTraditional landlineMobile / VoIP
Local (same area code)10 digits10 digits
US long distance1 + 10 digits10 digits
Emergency911911
🌐Universal+1 312 555 0123
🇪🇸🇲🇽Spain / Mexico00 1 312 555 0123
🇦🇺Australia0011 1 312 555 0123
🇯🇵Japan010 1 312 555 0123
HAVE THE FULL NUMBER?

Learn more about that number.

Check the line type and the carrier the number block was originally assigned to.

10 digits to see the carrier and line type of the number

05 / CARRIERS

Carriers in area code 312

Share of the number blocks by carrier and line type.

Landline

AT&T
67%
Verizon Business
8%
Lumen Technologies
6%
Sinch
4%
Windstream Communications
2%
Others
13%

Mobile

AT&T Mobility
33%
T-MOBILE USA
24%
Verizon Wireless
22%
USA Mobility
19%
Sinch
1%
Others
1%

Carrier shown is the original assignment of each number block and may differ today because of number portability.

06 / PREFIXES

Complete list of prefixes for area code 312

784 number blocks (NXX) assigned in this area code.

PrefixTypeCityCarrier
(312) 200 Landline Chicago Zone 01-Calumet Metro by T-MobileMETROPCS, INC.
(312) 201 Landline Chicago Zone 01-Franklin AT&TILLINOIS BELL TEL CO
(312) 202 Landline Chicago Zone 01-Superior AT&TILLINOIS BELL TEL CO
(312) 203 Mobile Chicago Zone 01-Wabash AT&T MobilityNEW CINGULAR WIRELESS PCS, LLC - IL
(312) 204 Landline Chicago Zone 01-Superior AT&TILLINOIS BELL TEL CO
(312) 205 Landline Chicago Zone 01-Calumet Verizon BusinessMCIMETRO ACCESS TRANSMISSION SERVICES LLC
(312) 206 Mobile Chicago Zone 01-Wabash AT&T MobilityNEW CINGULAR WIRELESS PCS, LLC - IL
(312) 207 Landline Chicago Zone 01-Canal AT&TILLINOIS BELL TEL CO
(312) 208 Mobile Chicago Zone 01-Wabash AT&T MobilityNEW CINGULAR WIRELESS PCS, LLC - IL
(312) 209 Mobile Northbrook West Verizon WirelessCELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL

Showing 10 of 784 prefixes

07 / FAQ

Frequently asked questions about area code 312

Where is area code 312 used?
Area code 312 serves Chicago and the surrounding area in Illinois, including Cook County.
What city is area code 312 from?
The main city of area code 312 is Chicago, IL.
What time zone is area code 312 in?
Area code 312 is in the Central Time (CT) time zone (America/Chicago).
Is 312 an overlay area code?
Yes. It shares its territory with 872. In an overlay, every call requires dialing all 10 digits.
How do I call a number with area code 312 from the United States?
Dial the 10 digits: 312 + 7-digit number. For some long-distance calls from a landline you may need to add a 1 first.
How do I call a 312 number from another country?
Dial your country's exit code (or +), then 1, then 312 and the seven-digit number. From a mobile you can use +1 312 XXX XXXX.
Which carriers use area code 312?
Most landline blocks belong to AT&T and most mobile blocks to AT&T Mobility. The carrier shown is the original assignment and may differ today because of number portability.
Is area code 312 for landlines, mobiles or both?
Both. About 68.24% of the number blocks are landline, 31.76% mobile.
How do I save a 312 number in WhatsApp or my phone?
Save it in international format: +1 312 XXX XXXX. That way WhatsApp, iMessage and Telegram recognize it from any country.
Is it safe to answer calls from area code 312?
The area code only shows the region a number was assigned to; it does not tell you who is calling. Scammers can fake any area code, so do not share personal or banking information with unknown callers, and let unknown numbers go to voicemail.
KEEP EXPLORING

Nearby area codes

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Other area codes in Illinois

217 · Springfield224 · Arlington Heights309 · Peoria331 · Aurora447 · Danville464 · Tinley Park618 · Collinsville630 · La Grange708 · La Grange730 · Centralia773 · Chicago779 · Rockford815 · Rockford847 · Northbrook872 · Chicago

View all Illinois area codes →