The numbers 1-, 2-, 3-, 6-, 7-, and 8- preceding University telephone extension numbers represent the prefixes 491, 332, 866, 467 (Evanston) and 482, 503, 908 (Chicago). The full prefix must be used to dial or fax to these extensions from outside the IT network. Evanston and other northern suburbs use both the 847 and 224 area codes. Chicago area codes are 312 and 773.