Abstract: Disclosed are a subscriber management system and a method thereof using OOB (Out Of Band) channel in the DMB (Digital Multimedia Broadcasting). The system of the invention transmits a message for the alteration of the subscriber information to terminal through the OOB, and receives the result of the transmitting of message, that the result comprises a success of the transmitting/alteration, a failure of the alteration, and an error of the transmitting. Therefore, the system is able to apply the alteration of subscriber information to the terminal as soon as the subscriber information is altered.