| 217 | Illinois (Champaign, Decatur, Urbana, Springfield and central Illinois) |
| 224 | Illinois (Waukegan, Des Plaines, northwest Chicago suburbs and northeastern Illinois, overlays with 847) |
| 309 | Illinois (Peoria, Moline, Rock Island, Galesburg and central western Illinois) |
| 312 | Illinois (downtown central Chicago area) |
| 331 | Illinois (West Suburban Chicago, overlays 630) |
| 447 | Illinois |
| 464 | Illinois Overlay of Area code 708 |
| 618 | Illinois (Alton, Belleville, Carbondale, Centralia, Mount Vernon and southern Illinois) |
| 630 | Illinois (Aurora, Naperville, and other Western Chicago suburbs, overlays with 331) |
| 708 | Illinois (Chicago Heights, Tinley Park, Cicero, Oak Forest, Oak Park, Berwyn, and southern and inner western Chicago suburbs) |
| 730 | Illinois Overlay of Area code 618 |
| 773 | Illinois (City of Chicago, excluding downtown; see also 312) |
| 779 | Illinois (Crystal Lake, Rockford, Joliet, and other outlying suburbs of Chicago; It overlays with 815) |
| 815 | Illinois (La Salle, De Kalb, Rockford, Freeport and northern Illinois including parts of the Chicago area such as Joliet, Plainfield and Crystal Lake, and is overlaid by 779) |
| 847 | Illinois (Arlington Heights, Buffalo Grove, Wauconda, Waukegan, Des Plaines, northwest Chicago suburbs and northeastern Illinois, and is overlaid by 224) |
| 872 | Illinois This Area code is scheduled to provide numbering relief to Area code 312 but no date has been assigned for this to go into effect. |
