A method for processing an authentication failed/authorization denied subscribers by intelligent network is disclosed in which when a call originated by a subscriber is authentication-failed or authorization-denied in a communication service network, a phone communication is connected to a service center or to a phone number designated by the subscriber of the corresponding terminal, or connected to a special service equipment such as an Intelligent Peripheral (IP), or is processed as a normal call. The identity of the subscriber can thus be recognized, and the subscriber's legitimacy can be determined. Additionally, various announcements, suitable to certain situations can be provided, or a normal call service can be provided to the subscriber. Additionally, communication between the subscriber and a person in charge of the subscriber in a service center can be established. A call of a subscriber that has been authentication-failed and authorization-denied is automatically traced and its history is automatically maintained.