Indiana | Illinois | Michigan NANP Expansion"Longer than 10 digit numbers" MyPlan for moving from 7D/10D to 8D/12D Chicago Illinois The Chicago area has moved from one area code (312) in 1988 to eight area codes with plans for a ninth (expected in 2015). Northern Illinois (815) has been overlaid and...

Indiana | Illinois | Michigan Illinois - Chicago Illinois Area CodesLast Change 2009 -- Next Changes -- Late 2014? - 447 overlays 217 Late 2015? - 464 overlays 708 Early 2017? - 730 overlays 618 Area code boundries on this page are based on information from 1994 and may not be 100% accurate. Written...