Pheonix Audio MT304 Video Conferencing Speakerphone Landline Telephone Accessory The USB is designed for Voice or Video over IP (VoIP) or can be used for playback of your computers media player or for recording a meeting. comes with a USB connection for your PC or MAC computer and a Daisy chain connection to link to other Quattro2's. All Quattro2's are expandable in an unlimited chain.