Area code 872 is a telephone area code in the North American Numbering Plan for Chicago in the U.S. state of Illinois. It is an overlay code for a numbering plan area that comprises those of area codes 312 and 773. The overlay commenced service on November 7, 2009. Its overlay status means it is assigned only to new numbers in the area and not to existing numbers using the 312 and 773 area codes. It is the third overlay area code in the region and the tenth area code to serve northeast Illinois.