Hello everyone! Newbie here. I recently purchased a used 2001 Mercedes E200 Estate which came with a factory installed Nokia 5110 phone and cradle. It also come with an Audio 10 CD HU and a CD changer in the boot. The phone works fine and interrupts the radio signal and volume when a call comes in. However, when I try to answer the call via the steering wheel buttons, the information displayed on the dashboard says "function not available". If however, I answer the call via the buttons on the phone itself, the call comes in through the radio and I can adjust the volume of the call via the steering wheel audio buttons. Do I need to have this coded at the Mercedes dealer for the steering buttons to work in answering and ending a call? Or, do I have to buy something else in order for this to work? I have read most of the threads in the audio and navigation but cannot see that this has been question has been asked or discussed. Digging through the cables near the CD changer, I saw a phone controller with the following #: A203-820-32-26. Aside from the black wire loom, I saw 2 orange or red nylon wires attached to this phone controller. I presume theses orange or red nylon wires are the fiber optic wires some of the threads discussed. One had an "Ampli" tag or marker while the other one had a "Telephone" tag. Any suggestions on making the steering buttons work to answer and end call would be greatly appreciated. Thanks in advance.