Contact Child Support Services There are several ways to reach Child Support Services (CSS). CSS Customer Service Center: 1-800-992-9457 Call the CSS Customer Service Center for all questions. The toll free number connects you with the Interactive Voice Response system available 24 hours a day, seven days a week. Information is available in English or Spanish. Have your Master Participant Index (MPI) number available. A menu describes your options. Press the appropriate number to go directly to the information you want or press "0" to speak to a customer service representative. Interactive Voice Response representatives are available from 7:30 a.m. to 5:30 p.m. Monday through Friday. Mail NC Child Support Services PO Box 20800 Raleigh, NC 27619-0800 Web You can also complete our feedback form and your questions are sent directly to a CSS representative. For more information on how to contact us visit the eChild Support website.