Area code 331
Area code 331 serves Aurora and nearby parts of Illinois, including Naperville, Wheaton and Downers Grove. It is on Central Time, which observes daylight saving time. 630 is an overlay for the same area.
Area code 331 at a glance
| State | Illinois (IL) |
| Main city | Aurora |
| Time zone | Central Time |
| UTC offset | UTC−6 in winter, UTC−5 in summer |
| Daylight saving time | Yes |
| Overlay codes | 630 |
Cities in 331
- Aurora
- Naperville
- Wheaton
- Downers Grove
An area code shows where a number was first assigned. Mobile numbers keep their area code when people move, so the person you’re calling may be somewhere else.
When you can call a 331 number
Federal telemarketing rules under the TCPA allow sales calls between 8 AM and 9 PM in the called person’s local time. Here is that window for a 331 number, shown in your own time zone.
General information, not legal advice. Some states add rules for Sundays, holidays or the number of calls. See our calling hours guide.
| If you’re on | You can call 331 between |
|---|---|
| Eastern | 9:00 AM to 10:00 PM |
| Central | 8:00 AM to 9:00 PM |
| Mountain | 7:00 AM to 8:00 PM |
| Arizona | 6:00 AM to 7:00 PM |
| Pacific | 6:00 AM to 7:00 PM |
See the time in 331 without leaving your CRM
Parse is a free Chrome extension that shows the local time and weather beside every phone number on the page.
Other area codes in Illinois
Questions about 331
What time zone is area code 331?
Area code 331 is on Central Time. It observes daylight saving time.
Where is area code 331?
Area code 331 is in Illinois. Its main city is Aurora, and it also covers Naperville, Wheaton and Downers Grove.
What are the legal hours to call a 331 number?
Under the federal TCPA, sales calls are allowed from 8 AM to 9 PM in the called person’s local time. Personal and informational calls are not limited by these hours.
What area codes overlay 331?
630 covers the same area as 331, so numbers in the same town can have either code.