How does the telephone in the Mercedes car work?

CL-2001. the old tele in the car. how does it work ? do i need to put a sim chip in it ? or is it wireless or by bluetooth? does the phone caller name appear on the screen?|||Is there a phone in there now ( a phone was a dealer installed option, it wasn't factory standard item )? If so, just register it. If there isn't, you'll have to install a phone integration kit and then buy a Bluetooth puck so you can use any Bluetooth enabled phone with the system in the car.|||Try the manual for the car, if you have lost it just type it in ebay or something and im sure something would pop up.