Service of subpoenas and payment of witness and mileage fees shall be as provided in Section 10-106 of the Public Utilities Act. No person served with a subpoena which has been issued at the instance of any party to a proceeding before the Commission shall be required to respond to such subpoena unless the appropriate fees for attendance and travel are tendered at the time of service.

(Source: Amended at 10 Ill. Reg. 10481, effective May 30, 1986)