🇺🇸United States • Illinois

Illinois Calling Codes
312, 773 & More

Calling Chicago or the suburbs? Illinois has a complex area code system. Whether it's 312 for Downtown or 630 for the suburbs, connect instantly from your browser.

How to Dial
Calling Chicago (US)Line Active
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How to Call Illinois Step-by-Step

Illinois requires 10-digit or 11-digit dialing due to the high density of phone numbers, especially in the Chicago metro area.

1

Country Code (+1)

Dial +1 or 001 if calling from outside North America.

2

Area Code

Dial the 3-digit area code.
312773630
See table below for correct code.

3

Local Number

Dial the 7-digit subscriber number.
Example: +1 312 555 0199

Understanding Chicago Area Codes

Chicago is unique because it splits area codes by geography within the city limits.

312
Downtown / The Loop
773
Neighborhoods / Airports
872
City-wide Overlay

Illinois City & Region Guide

Find the correct area code for major Illinois cities.

CityRegionArea Codes
Chicago (Downtown)Cook County312
Chicago (Neighborhoods)Cook County773
Chicago (Overlay)Cook County872
Aurora / NapervilleWest Suburbs630 / 331
Schaumburg / EvanstonNorth Suburbs847 / 224
Joliet / Oak LawnSouth Suburbs708 / 464
RockfordNorthern IL815 / 779
Peoria / BloomingtonCentral IL309
Springfield / ChampaignCentral IL217
Belleville / CarbondaleSouthern IL618

Why Use VoIP to
Call Illinois?

Connecting with business partners in Chicago or family in Springfield shouldn't be expensive. StartACall provides instant connectivity without carrier fees.

  • Reach any 312, 773, or 630 number instantly
  • No roaming charges for international callers
  • High-quality voice for business calls
  • Works on any browser, mobile or desktop

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Frequently Asked Questions

What is the area code for Downtown Chicago?

The area code for Downtown Chicago (The Loop) is 312. This is one of the original area codes and is highly recognizable.

What is the difference between 312 and 773?

312 covers the central business district (Downtown). 773 covers the rest of the city, including neighborhoods like Lincoln Park, Wrigleyville, and Hyde Park, as well as both O'Hare and Midway airports.

Do I need to dial 1 before the area code?

If you are calling from a landline within the US, you usually dial 1. If you are calling from a mobile phone or VoIP service like StartACall, you can just dial the 10-digit number (Area Code + Number), or +1 followed by the number.

What time zone is Chicago in?

Chicago and all of Illinois are in the Central Time Zone (CT). This is one hour behind New York (Eastern Time) and two hours ahead of Los Angeles (Pacific Time).

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Illinois area codes beyond the Chicago table: geography, overlays and timing

In short

Illinois splits into a dense Chicago cluster and a set of broad downstate codes, and knowing which side of that divide a number sits on tells you a lot about who will answer. This guide maps the metro rings, explains the downstate overlays, and gives Central Time windows for callers in Europe, Africa and Asia.

Chicago's rings of codes

The city itself uses 312 with its 872 overlay in the downtown Loop area and 773, also overlaid by 872, for the rest of Chicago. The suburbs form a ring: 847 and 224 to the north, 630 and 331 to the west, 708 and 464 to the south and southwest.

For a caller abroad the ring structure mostly signals commuting patterns. A 312 number suggests a downtown office likely staffed 9am to 5pm, while an 847 or 630 number may be a home or a suburban business park. All are dialed identically, +1 plus ten digits.

Chicago's downtown 312 numbers are prized by businesses that want a city identity, and a quiet market in old numbers persists, so a 312 line can belong to a firm based anywhere in the metro. Treat the ring structure as a probability, not a guarantee, when guessing who will answer. Number listings age quickly in the city, so verify current details online before assuming anything about location.

Downstate: big territories, fewer numbers

Outside the metro, 815 with its 779 overlay covers Rockford, Joliet and the north beyond the suburbs. Central Illinois splits between 217 with overlay 447 around Springfield and Champaign, and 309 with overlay 861 for Peoria and the Quad Cities area. The entire southern third, including Carbondale and the Metro East near St. Louis, uses 618.

State government answers on 217 numbers in Springfield, while the universities put 217 and 309 on many admissions and administrative lines. Downstate businesses often open at 8am Central, an hour of extra morning for European callers compared with typical Chicago offices.

Agricultural Illinois works the land's clock. Grain merchants and farm services across 217, 309 and 618 territory answer early and fade by late afternoon, and during the October harvest phone contact becomes unreliable altogether. Email or early morning calls work better in those weeks than repeated afternoon attempts.

Central Time windows and dialing practice

All of Illinois observes Central Time, six hours behind UTC in winter and five in summer. From London, 3pm to 11pm covers the Illinois business day and evening. From Lagos the gap is seven hours in winter, and from Delhi, Illinois mornings fall around 7:30pm to 10:30pm local.

Every number is +1, area code, seven digits. Overlay regions already dial ten digits locally, so printed numbers are complete. Calling with StartACall costs the same per minute for a 312 downtown landline and a 773 mobile, pay-as-you-go from the browser with no connection fee, and the first call is free.

O'Hare airport lines, downtown hotels and hospital switchboards answer around the clock, so urgent calls always have a route. For everything else, Chicago's business day runs 9am to 5pm Central with the usual lunchtime dip around noon, which corresponds to 6pm or 7pm in most of Europe.

Frequently asked questions

What area code is downtown Chicago?+

The Loop and central Chicago use 312, with 872 as an overlay. The rest of the city uses 773, also overlaid by 872, so all three are genuine Chicago city codes.

What area code is Springfield Illinois?+

Springfield, the state capital, uses 217 along with its overlay 447. The code also covers Champaign, Urbana and Decatur in central Illinois. State government lines in Springfield answer on 217 numbers.

Which area code covers southern Illinois?+

Area code 618 serves the southern third of the state, including Carbondale, Belleville and the Metro East suburbs across the river from St. Louis. It is one of the few Illinois codes without an overlay.

What time is it in Illinois compared with London?+

Illinois is on Central Time, six hours behind London in winter and usually five in summer. Noon in Chicago is 6pm in London for most of the year. The gap briefly changes when the two regions switch clocks on different dates.

Is it cheaper to call an Illinois landline than a mobile?+

No difference. US mobiles use the same geographic codes as landlines, and StartACall bills both at one per-minute rate with no connection fees or subscription. Both are dialed +1 plus ten digits from any country.

Last reviewed June 2026Reviewed by the StartACall calling teamDialing rules cross checked against ITU international dialing procedures
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