Area code 312 – Illinois
312 is one of the original area codes, in service across Illinois since 1947. All but a handful of its 786 number blocks are allocated (784 of 786), so it is effectively exhausted. AT&T is the largest holder with 56.4% of blocks, ahead of Verizon at 12.0%. It shares its geography with overlay codes 872, so local calls take all ten digits. FTC complaints naming a 312 caller ID totalled 494 in the 33 days to 30 October 2026 (214th of 422 ranked codes). The dominant complaint type is “Other”.
Who holds 312 number blocks
Share of the 784 assigned NXX blocks (99.7% of the 786 possible), across 36 carriers. This is share of number blocks, not of subscribers.
- AT&T56.4%
- Verizon12%
- T-Mobile9.1%
- Lumen4.6%
- Spok4.2%
- Other CLEC / VoIP3.8%
- Onvoy2.6%
- American Messaging1.8%
- Windstream1.7%
- Bandwidth1.5%
- Peerless1.3%
- Charter0.4%
- Comcast0.4%
- Vonage0.1%
- VoIP Innovations0.1%
- TPx0.1%
Spam complaints naming 312
FTC Do Not Call complaints where the caller ID was a 312 number, 28 Sep – 30 Oct 2026 (33 days). Caller IDs on spam calls are frequently spoofed, so these are complaints about the code, not calls proven to originate in it.
Rate centers in 312
NANPA allocates number blocks to rate centers and records their names abbreviated to ten characters, so these are NANPA's codes rather than place names – CHAMPAURBN is Champaign-Urbana, NWYRCYZN01 is a New York City zone. We show them unchanged instead of guessing at the full names. Showing the largest 5 of 8.
Timeline
- 1947 312 assigned in the original North American Numbering Plan.
More about 312
Separate pages for the questions that need their own answer: what time it is there, what the complaint data says, who holds the number blocks, and how the code compares with the one it shares its area with.
Frequently asked about 312
What state is area code 312?
Illinois. It covers the same area as 312/872.
Can I still get a 312 number?
Only from recycled stock. 784 of the 786 available blocks are already allocated, so new numbers in the area normally come from the overlay codes (312/872).
Is a call from 312 a scam?
Not by itself. 312 drew 494 FTC complaints in the 33 days to 30 October 2026, 214th of 422 ranked codes – mid-pack or lower. Spam callers spoof caller IDs, so the only useful check is the full number. The most reported category here is “Other”.
Which carrier owns 312 numbers?
AT&T holds the largest share of assigned number blocks at 56.4%. The rest is spread across 3 other carriers. This is share of number blocks, not of subscribers – people keep their numbers when they switch carriers.
Do I need to dial 10 digits in 312?
NANPA records the local dialing plan for 312 as “1+10D”.
Sources and verification
- NANPA – NPA Database (npa_report.csv), file date 11/01/2026, retrieved Nov 1, 2026
- NANPA – CO Code Assignment Records, All States (utilized), file updated 11/01/2026, retrieved Nov 1, 2026
- FTC – Do Not Call Reported Calls Data, 25 daily files 28 Sep – 30 Oct 2026, retrieved Nov 1, 2026
NANPA dialing note for this code: “1+10D”. Reviewed by the data desk. Spotted an error? Request a correction.