312 area code
Chicago area, Central Time.Area code 312 covers Chicago in Illinois, on Central Time. 872 covers the same area.
Right now in Chicago
Central Time (CST, UTC-6; CDT, UTC-5 in summer)
Calling hours: Every day, 8 AM to 9 PM (the federal rule)
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Where 312 numbers come from
Numbers are issued by rate center, a billing area named for its main town. 312 has 1. Each one's share is how many 312 numbers start there. Its biggest metro area is Chicago-Naperville-Elgin, IL-IN.
- Chicago100%
Share of exchanges (blocks of 10,000 numbers). Source: NANPA rate center and exchange reports, November 10, 2026
When can you call a 312 number?
Sales calls to homes and cell phones have legal hours, set by the federal rule. Hold every 312 number to them, since you can't tell a work line from a personal cell.
What applies to 312Every day, 8 AM to 9 PM
- Federal (TCPA and FTC rule)Every day, 8 AM to 9 PMCalls to residential and mobile numbers. Most calls to businesses are exempt from the FTC's rule.47 CFR 64.1200(c)(1); 16 CFR 310.4(c) (opens in a new tab)
Local time comes from the area code, not from where the person is today. Mobiles keep their number when they move. Calling hours here are a guide, not legal advice. Every state's calling hours, with sources
312 and 872
312 is one of the original area codes from 1947, and 708 and 773 were later split off from it. 312 and 872 cover the same area, so new numbers can get either code and neighbors can have different area codes. 312 holds 73% of the area's exchanges; 872 holds the rest. Local calls take all 10 digits.
- 1947312 starts
- 1989708 split off
- 1996773 split off
- 2009872 overlay
Source: NANPA area code database
Calling a list of 312 numbers?
Paste it into the free phone number validator. It checks every number, finds each one's time zone and sorts the list by who you can call right now.
312 area code FAQ
What area code is 312?
312 is an Illinois area code for Chicago.
What time zone is the 312 area code in?
Central Time (CST, UTC-6; CDT, UTC-5 in summer).
Is 872 the same as 312?
Same area, different code. 312 and 872 cover the same area (an overlay), so new numbers can get any of them and local calls take all 10 digits.
What are the calling hours for 312 numbers?
Every day, 8 AM to 9 PM, local time, under the federal rule.
When did the 312 area code start?
In 1947: it's one of the original area codes.
Calling 312 numbers? Reach more of them.
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