312 Area Code

What 312 actually covers

312 is the area code of central Chicago only. Since 1996 it has been an enclave of a few square miles: roughly everything east of Western Avenue, south of North Avenue and north of 35th Street, with Lake Michigan on the fourth side. That takes in the Loop, the Near North Side including the Magnificent Mile, River North and Streeterville, the West Loop and Fulton Market, the Near West Side with the medical district, the Near South Side and the South Loop, and the museum campus.

Everything else in the city, from Wrigleyville to Hyde Park to O'Hare, is 773. The suburbs are 708, 847, 630 and 331. So a 312 number belongs to the business core of the city, and a caller claiming to be from "the suburbs" or "the North Side" with a 312 number has already told you something is off.

Since 2009 both 312 and 773 have been overlaid by 872, which covers the whole city. Any Chicago address, downtown or not, can be issued an 872 number, and all local calls are dialled with ten digits.

How 312 got here

• 1947: 312 was one of the original area codes and covered most of the Illinois side of the Chicago metropolitan area.
• November 1989: the suburbs were split off as 708, leaving 312 with the city proper.
• October 1996: with pagers, fax lines and cell phones exhausting the code within a few years of the first split, the city outside downtown became 773. 312 shrank to the central business district and became one of the smallest area codes in the country.
• November 2009: 872 was overlaid on both 312 and 773 and ten-digit dialling became mandatory across the city.

The 1996 split is why 312 reads as "downtown Chicago" to locals in the way 212 reads as Manhattan. Law firms, banks, trading firms, the big hospitals on the Near West Side, City Hall and the county courts all carry 312 numbers. That association is exactly what makes 312 attractive to spoof: a call displaying 312 looks like it comes from an institution, not from a robocall floor.

What a real 312 caller usually looks like

• Landline on an established carrier is the expected result. City of Chicago departments, Cook County offices and courts, the federal courthouse, the medical district hospitals, universities, hotels and the downtown offices all sit on 312 landlines.
• Mobile 312 numbers exist but are less common than in most cities, because the pool of 312 numbers was tight from 1996 on and most new mobiles went to 773 and later 872. A mobile 312 is usually an older number or one that was ported over on purpose.
• VoIP results deserve a second look. Plenty of downtown businesses run legitimate VoIP lines, but a VoIP line with an unfamiliar reseller is also the standard footprint of a spoofed call.
• Ported means the number has changed carriers at least once; combined with a recent VoIP carrier it often means the number was bought for its downtown look.

The line type does not tell you who is calling, but it tells you whether the caller's story fits. A sheriff's deputy, a court clerk or a utility does not call from a VoIP reseller.

Scams that use 312 caller IDs

Cook County deputy and jury duty calls. The Cook County Sheriff's Office has warned repeatedly about callers using the real names and titles of its employees, police jargon and spoofed numbers, who claim the target missed jury duty or has a warrant and must pay a cash "bond" to avoid arrest. Recent reports in the south suburbs involved demands of $2,000 to $7,000. The Sheriff's Office does not call to seek payment, notify people of citations or warrants, or accept payment through money transfer apps. Get the caller's name and badge number, hang up, and call the Sheriff's Police at 708-865-4896.

Federal court impersonation. The federal court for the Northern District of Illinois, which sits in the Loop, has issued its own warning about callers claiming to be court officers or U.S. Marshals demanding fines for missed federal jury service. Federal courts never ask for payment or personal financial information by phone.

ComEd disconnection threats. A caller claims to be ComEd, says power will be cut within the hour, and directs the target to pay by prepaid card, cryptocurrency or a payment app, or to call back an "automated line". ComEd says it never demands immediate payment under threat of disconnection and never asks for prepaid cash cards, Bitcoin or apps like Zelle, Venmo or Cash App. The Illinois Attorney General issued a separate alert about the cryptocurrency version. ComEd's published line for reporting a suspicious call is 1-800-334-7661.

Tollway and I-PASS texts. Since spring 2024 the Illinois Tollway has been warning about texts claiming unpaid tolls with a "final notice" and a link to a fake payment page; the Chicago area has been hit harder than most of the country. The Tollway does not send texts demanding payment. Check your I-PASS account on the official site, not through a link.

Medical district billing calls. With Rush, UI Health, Stroger and Northwestern Memorial all inside or beside the 312 boundary, a call "from the billing office" about an outstanding balance is plausible. Real billing departments do not take card numbers on an unsolicited call and never ask for a one-time code sent to your phone.

Neighbour spoofing. Robocall operations display a 312 number sharing your first six digits so the call looks like it comes from your building. The number shown usually belongs to an unrelated downtown line, which is why some 312 numbers collect reports from people who were never actually called by them.

How to check a 312 number

1. Enter the ten-digit number in the panel at the top of this page. The 312 is already filled in.
2. Compare the line type and carrier with what the caller claimed. Courts, utilities and agencies call from established landlines, not VoIP resellers.
3. Read the risk level and community reports. Several "scam" or "robocall" reports within days of each other mark a live campaign.
4. Still unsure? Unlock the risk details for the fraud score and abuse history, or call the organisation back on the number printed on its official site or your bill.

Where to report a 312 scam call

• Illinois Attorney General, Consumer Fraud Hotline: 1-800-386-5438 (Spanish 1-866-310-8398), or the online complaint form at illinoisattorneygeneral.gov.
• Cook County Sheriff's Police: 708-865-4896 for deputy impersonation and jury duty scams.
• ComEd: 1-800-334-7661 to report a utility impersonation call.
• City of Chicago: call 311 to reach the police non-emergency line if money was lost.
• Federal Trade Commission: reportfraud.ftc.gov. Reports feed the complaint data carriers use to block robocallers.
• CallerTracer: report the number on the Who Called Me page or straight from a lookup result. It shows on this page and on every lookup of that number within minutes.

Frequently asked questions

Is 312 all of Chicago?

No. Since 1996, 312 has covered only the central part of the city, roughly the Loop and the near neighbourhoods around it. The rest of Chicago is 773, and 872 overlays both.

Are new 312 numbers still issued?

Rarely. The pool has been tight since the 1996 split, and most new lines anywhere in the city, downtown included, come out as 872.

Does a 312 number mean the caller is downtown?

Only that the number was issued there. Mobile and VoIP numbers move with their owners, and a spoofed call can show any number at all. Use the carrier and line type from a lookup, not the area code, to judge where a call came from.

What time zone is 312?

Central Time, with daylight saving from March to November. The clock at the top of this page shows the current time in Chicago.

Which area codes are next to 312?

773 surrounds it on three sides and 872 overlays both. 708 covers the near south and west suburbs, 847 and 224 the north suburbs, and 630 and 331 the west suburbs.