331 Area Code
Western suburban Chicago, Illinois
Area code 331 is located in Western suburban Chicago, Illinois. It covers Aurora, Naperville, and surrounding areas in the Central time zone (UTC-6). Administered by NANPA.
Where is area code 331?
Area code 331 is located in Western suburban Chicago, Illinois. It covers Aurora, Naperville, and surrounding areas in the Central time zone (UTC-6).
Cities Covered by Area Code 331
Area code 331 primarily serves the Western suburban Chicago area of Illinois. The exact coverage includes Aurora, Naperville, and Bolingbrook, along with surrounding communities and suburbs.
Time Zone
Central Time — UTC-6
Area code 331 operates in the Central Time Zone. When calling 331 numbers from a different time zone, be sure to account for the time difference to reach people during business hours.
About Area Code 331
Area code 331 was introduced in 2007 as a geographic area code serving Western suburban Chicago, Illinois. It remains the primary area code for this region. Area codes are administered by NANPA (North American Numbering Plan Administration), the organization responsible for managing phone number resources in the US and Canada.