Participants with questions should contact the Service Center at 877.644. Please schedule a Local Office: In-Person Appointment or call us at 1-855-457-2489.The State of Illinois Deferred Compensation Plan is a supplemental retirement program for State employees. Need more information about deferred compensation plans? Forms and Help. Forms. Help. Left justify and fill with blanks. 249-263. Employer Contact Phone. Number. 15. Call 1-888-867-5175 Email us.