a hands - free kit for cell - phones combines the wireless capabilities of bluetooth and the sound and visual functionalities of a tape player . a device that has a shape of a conventional magnetic cassette comprises a bluetooth module . the module automatically detects a data communication initiated with the portable apparatus over a wireless network when the device is inserted in the tape player . then the module automatically configures the apparatus to transmit to the device a low frequency signal representative of the communicated data . the device converts the received low frequency signal into a magnetic signal further communicated to the tape player for play out and / or display . thus , when a cell - phone rings , a driver inserts the device in his tape player and the cell is picked up and the conversation played out loud on the loud speakers in the car .