Area code 773: Illinois
Area code 773 is a US state area code for Illinois, on Central Time. It has 785 prefixes in service across 11 rate centers, the largest being Chicago Zone 03, Chicago Zone 01 and Chicago Zone 02. It shares its area with 872, so local numbers there can start with any of them.
Local time in area code 773
America/Chicago
Prefixes in service
785 of 792 possible
11 rate centers
Area code 773 facts
| Location | Illinois, United States |
|---|---|
| Time zone | Central Time |
| Overlays | 872 |
| Split from | 312 |
| In service since | October 12, 1996 |
| Local calls | 1 + 10 digits |
| Carrier | Not shown. An area code is where a number was issued; numbers port between carriers. Check line type |
Which cities and towns use area code 773?
NANPA records each prefix against a rate center, the local billing area a number belongs to, usually named after its main town. These are the 773 rate centers with the most prefixes in service.
| Rate center | Prefixes |
|---|---|
| Chicago Zone 03 | 170 |
| Chicago Zone 01 | 124 |
| Chicago Zone 02 | 79 |
| Chicago Zone 07 | 78 |
| Chicago Zone 04 | 75 |
| Chicago Zone 10 | 72 |
| Chicago Zone 06 | 56 |
| Chicago Zone 08 | 45 |
| Chicago Zone 05 | 40 |
| Chicago Zone 09 | 26 |
| Chicago Zone 11 | 20 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 773 number?
NANPA's dialling plan for 773: local calls inside the code take 1 + 10 digits, toll calls 1 + 10 digits. From another area code, dial 1 first. From abroad, use +1. The examples use 555-0147, from a range reserved for fictional numbers.
| Local call inside 773 | 1-773-555-0147 |
|---|---|
| From another US or Canadian area code | 1-773-555-0147 |
| From outside North America | +1 773 555 0147 |
| E.164, for CRMs and SMS tools | +17735550147 |
When did area code 773 start?
Area code 773 went into service on October 12, 1996, split from 312. Today 773 and 872 cover the same area as an overlay, which is why 10-digit dialling is needed for local calls there.
Tools for 773 numbers
- Area code lookup
Look up any code or a whole list of numbers, or find the codes for a state or city.
- Area code time zone
Local time for a list of numbers, with a callable-now flag.
- NPA-NXX lookup
Rate center and state for one prefix, a level below the area code.
- TCPA calling hours checker
Whether it's inside the federal 8 a.m. to 9 p.m. calling window there now.
Next step
A 773 number tells you where it was issued, not what it is now.
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Area code 773 questions
- What state is area code 773?
- Area code 773 is in Illinois, United States. Its largest rate centers by number of prefixes are Chicago Zone 03, Chicago Zone 01, Chicago Zone 02, Chicago Zone 07 and Chicago Zone 04.
- What time zone is area code 773 in?
- Central Time.
- What area codes overlay 773?
- 872. An overlay adds a new code to the same area instead of splitting it, so neighbours can have different area codes and local calls need 10 digits.
- When did area code 773 start?
- Area code 773 went into service on October 12, 1996, split from 312.
- Is a 773 number a cell phone or a landline?
- The area code can't tell you. In the US and Canada mobiles, landlines and VoIP lines share area codes and prefixes, and numbers move between carriers and line types. Only a live line-type lookup answers it for one number.
- How many phone numbers does area code 773 have?
- 785 of its 792 possible prefixes are in service, and each prefix holds up to 10,000 numbers. That counts prefixes assigned to carriers, not numbers in use.
Other area codes in Illinois
Sources
Location, overlays, in-service date and dialling plan: NANPA NPA database, file dated 10/16/2026. Prefixes and rate centers: NANPA central office code assignments, 10/17/2026. Time zones mapped to the IANA time zone database. By the SimpleVerifier Team; how we build these pages.