How the GSM/Bluetooth wireless connection works
When the car ignition is switched on, a wireless connection is
established between the compatible mobile phone and the car
kit phone via Bluetooth SIM Access Profile. The car kit phone
requests the compatible mobile phone to log out of the GSM
wireless network and to deactivate the mobile phone
components required for the GSM connection. The car kit phone
then uses Bluetooth SIM Access Profile to access the SIM card
inserted in the compatible mobile phone (remote SIM card) and
utilises this card’s profile to log into the GSM network. Now the
car kit phone handles all incoming and outgoing calls and
messages while accessing the SIM card of the compatible
mobile phone.