The serious answer: Mercedes has the worst bluetooth of any auto
manufacturer, bar none.
First of all the car has to be wired for bluetooth. A new Mercedes may be
billed as Bluetooth ready, but that does not mean the Bluetooth wiring and
microphone are actually installed in the car. If they were not factory
installed then the dealer will charge around $1500 to do it.
If the car is actually wired then you have to buy a separate dedicated
cradle for the few useless phones Mercedes recognizes or their generic
Bluetooth receiver. Either will cost another $400.
Alas, the implementation of Bluetooth by Mercedes is, to be charitable,
My two year old BMW recognizes and works well with even the cheapest no name
Bluetooth phone. Ditto my mother's American car.
It is difficult to register bluetooth phones with the Mercedes and difficult
to initiate calls using the Mercedes console, presuming your car is
"Bluetooth ready" to begin with so you have telephone controls built into
the car, and receiving calls is fitful at best.
Good luck. You will need it. You may want to look into non-Mercedes options
although I do not know what they are.