Navi Plus and mobile phone adapter Siemens

With my new A6 Avant 1.9 TDI (BJ 2004) with Navi Plus and hands-free device, I ordered a mobile phone adapter (Cullmann) for a Simens S45i from Audi. This adapter with spiral cable is inserted into the middle armrest. The vehicle has no voice control for the hands-free and also no multifunction steering wheel. Now I would like to operate the mobile phone via the buttons on the Navi, or also see the caller and other information in the display. However, this does not work. This is quite cumbersome. Am I just too stupid or is it on the adapter or on the Siemens S45, which may not be 100% compatible with the Navi Plus. Or are there other adapters that offer these functions, e.g. read phone book from SIM? Don’t skin my hands-free speech, or I don’t know. User manuals and friendlic he Audi staff can’t help me either.