You can not connect to audio service (handsfree in your case) with using simple RFCOMM connection. The device waiting for SCO connection and it's waiting for specified AT commands sequence. As soon as device does not receive AT command it drops connection. You should know, that this type of connection will establish only RFCOMM (control channel) link and will not allow you to send (and receive) any audio data. You have to establish SCO link to send audio data. Unfortunatly such feature was partialy implemented in BTF and is implemented in WCL (but is not available for public usage yet). Also you should know, that it is possible with using Toshiba, BlueSoleil or WidComm drivers (each one has own limitations). It is impossible with using MS bluetooth drivers.