A mobile phone preparation kit is available on request for Bluetooth® connection of mobile phones which only support the Handsfree Profile (HFP). For connection by HFP, PCM or CDR-30 acts merely as a hands-free system. Here, too, the mobile phone can remain tucked away. Only the basic phone functions can be operated using PCM or CDR-30. The GSM connection is established via the aerial of the mobile phone. The mobile phone preparation kit is available with or without cradle.