The state of Illinois offers the I-PASS, which is a system that lets drivers pay for tolls online, as of 2015, according to the website of the Illinois Tollway. I-PASS customers receive transponders that they mount on their windshields that allow them to pass through tolls quickly on roads in the E-Z Pass system, including the Indiana Toll Road and Chicago Skyway.
As of 2015, the cost of getting started with I-PASS is $30, which includes $20 in prepaid tolls and a $10 refundable deposit, as stated by the Illinois Tollway website. Once the transponder is mounted on the driver's windshield, a radio antenna sends a signal to the transponder to deduct the proper amount from the I-PASS account. Accounts are funded and refilled online as needed.