DeKalb, IL is currently using an area code overlay in which area codes 779 and 815 serve the same geographic area. Ten digit dialing (area code + seven digit number) is necessary.
In addition to DeKalb, IL area code information view area codes 779 and 815 details and Illinois area codes.
DeKalb, IL is located in DeKalb County and observes the Central Time Zone.
View our Times by Area Code tool.