Aspects of the disclosure provide an apparatus that includes interface circuitry and processing circuit. The interface circuitry is configured to receive contact information provided by a terminal device for a contact entry in the terminal device. The contact information includes at least one communication attribute parameter for representing an attribute of the contact entry for communication, and the communication attribute parameter includes one or more parameter characteristics. The processing circuitry is configured to determine whether the contact information of the contact entry is abnormal with one or more abnormal parameter characteristics, generate, when the contact information of the contact entry is determined to be abnormal, a new filtering rule for filtering contact entries according to the one or more abnormal parameter characteristics, and add the filtering rule to a rule base to obtain an updated rule base.