Answering, ending and rejecting a call. Voice dialing, dial-back and redialing. Built-in microphone for speaking and loudspeaker to listen to calls and music. Built-in li-on rechargable battery. Individual wireless earpiece that provides private talking channel. Bluetooth connectivity up to 10m, wireless earpiece connectivity up to 4m. LCD screen displays incoming caller ID and caller name,synchronous with cell-phone. Integrated newest MP3 player, it can play music from Micro SD memory cards. USB interface for software framework upgrades. Integrated newest MP3 player,it can play MP3 format music from Micro SD,USB drive or cell-phone. Bluetooth specification: BC2.1 with A2DP. Bluetooth operation: max 10 meters. Range of frenquency: 2.4GHz. Input voltage: DC 12V 24V.