Ameren IP is an energy delivery company based in Decatur, Illinois, and serves 650,000 natural gas and electricity customers in a 15,000 square-mile territory across Illinois, including Monticello.  Ameren IP was formed when Ameren purchased Illinois Power in 2005. 

                  Ameren IP
                  1-800-755-5000.
                  P.O. Box 2522
                  Decatur, IL 62525-2522