The change was announced this week by the Illinois Commerce Commission (ICC), which oversees telephone service throughout Illinois. The area affected is covered by the existing “217” area code, which includes Champaign-Urbana, Decatur, Quincy, Springfield, and other towns and cities in the middle portion of the state. Telephone service providers are reporting to the ICC that numbers within the 217 area code are running out and they must ask for a new overlay code. The overlay code number will be 447, and the ICC and the industry will transition the new overlay code into use during a six-month period in late 2020 and early 2021.
Telephone users in areas of Illinois north of Interstate 80, including greater Chicagoland, are already familiar with overlay codes. In an overlay-code region of Illinois, the dialer must use all ten digits to dial a phone number, including numbers within his or her local area. The ten-digit number for local calls within Central Illinois will become voluntary on August 29, 2020, and mandatory on February 28, 2021. On and after that date, people in the affected area who try to dial a seven-digit number will get a recorded voice telling them to dial again. In April 2021, some new phone customers in Central Illinois will start to get the 447 area code assigned to them. After this 2020-2021 transition, the only remaining non-overlay code areas left in Illinois will be the areas served by the 309 area code, which operates in the Peoria-Quad Cities area, and the 618 area code, which serves southern Illinois.