There is a problem that, if a silent period is generated to a real-time application such as VoIP due to handover using BBM method, a user has a sense of anxiety and misunderstands that communication is completely disconnected. If the silent period is generated to the real-time application such as VoIP due to packet loss at handover, a terminal activates handover alarm (beep sound, for example), indicating that handover is in progress, during the silent period. Thereby, it notifies the user that the silent period is caused by handover and prevents user's misunderstanding that communication is completely disconnected.