I have a 1987 300E that came with the usual Becker audio system. It also came with an analog cell phone that was integrated nicely into the audio system: It has a microphone, audio was through the speakers, and one could dial through the radio preset buttons.

The analog cell phone has been removed, though I still have all of the parts. It just is not useful any longer.

How do I include this sort of phone system into a more modern radio/adapter/whatever? I am generally aware of bluetooth options, but those rely mostly on the cell phone to do the heavy lifting.

Is what I desire possible, or has technology passed this by?