625 ILCS 5/18c-1801
It shall be the responsibility of each person subject to the licensing or ratemaking provisions of this Chapter to keep on file with the Commission the name of a person upon whom notices, orders, or process in administrative or judicial proceedings under this Chapter may be served, together with a current address within the State of Illinois at which such person may be served. The Commission shall maintain a file of such "agents for service of process." Service of any Commission notice, order, or process on the agent for service of process at the address shown in the file shall be conclusively presumed to be service on the carrier, broker, or other person. If a person fails to make the filing required herein, the person may be served at the most current address in other records of the Commission, or at the address on file with the Secretary of State for service of process, and the same conclusive presumption shall apply.
625 ILCS 5/18c-1801