773 area code — Chicago, IL geographic
The 773 area code covers Chicago, Illinois, Central time zone, and dates back to October 12, 1996. Together with 872 it forms the 773/872 overlay. Because of number portability and VoIP, the area code tells you where the number was issued, not where the caller is right now.
NANPA lists 785 active NXX prefixes in 773, assigned to 22 carriers. 484 of those prefixes are pooled — shared between carriers in thousands-number blocks. The code spans 11 rate centers (billing localities).
Official projections put exhaust for the 773/872 complex at 4Q 2046.
The dialing plan is 1+10D for home-NPA local calls and 1+10D across codes.
Use this page to decode where 773 numbers come from — and remember that spoofing means the screen can lie about everything except your own caution.
Its parent code is 312, which it left in 1996.
Largest localities in 773
| Locality (rate center) | Active prefixes | Also served by |
|---|---|---|
| Chicago Zone 03 | 170 | 708, 872 |
| Chicago Zone 01 | 124 | 312, 630, 708, 847, 872 |
| Chicago Zone 02 | 79 | 872 |
| Chicago Zone 07 | 78 | 312, 872 |
| Chicago Zone 04 | 75 | 312, 872 |
| Chicago Zone 10 | 72 | 872 |
| Chicago Zone 06 | 56 | 872 |
| Chicago Zone 08 | 45 | 872 |
| Chicago Zone 05 | 40 | 872 |
| Chicago Zone 09 | 26 | 872 |
FAQ
Why do 872 and 773 cover the same place?
They are overlays: when a code runs low on numbers, a new code is added over the same territory instead of splitting it. The 773/872 complex shares one service area, and local calls are dialed with 10 digits.
Will 773 run out of numbers?
NANPA's current forecast projects exhaust in 4Q 2046 — decades of capacity remain.
Why am I getting spam calls from 773 numbers?
Scammers spoof recognizable area codes so calls look local or familiar. A displayed 773 number does not prove the call originated there — see our guide to spotting spoofed calls.