A communication system providing a multimedia service which enables requesting a communication network to cancel a registration for a calling terminal as a bad terminal in the communication network. Typically, the calling terminal is connected to a calling-side communication network; and if the calling terminal is registered as a bad terminal in a called-side communication network, the calling-side communication network requests the called-side communication network to cancel the registration. The calling terminal may be informed that reception of a communication in the communication system has been restricted.