A hands free device for a cellular phone which has a telephone transceiving unit for a mobile radio network and in addition a communication device for the wireless transmission of audio and data signals, with a housing in which a communication device forming a wireless communication connection with the communication device of the cellular phone is located, provides for the activation by a cellular phone without or at least without voluminous permanent installations in a motor vehicle in that a telephone transceiving unit for a mobile radio network is integrated in the housing, which telephone transceiving unit is set up for receiving user-specific data from a cellular phone via the communication device and providing a user-specific cellular phone function, specified by the user-specific data, through the telephone transceiving unit, the telephone transceiving unit is connected to a display in the housing and the housing has a power supply connection and an antenna connection.