On the E39, the factory telephone module lives in one of two places:Ted, I received my unit today and installed it in a few minutes. Love how simple things are. The only hiccup i am experiencing is same as above quoted. I can here the person I am calling but they are not able to hear me. Can you share a link to where you mentioned above about the factory module in the trunk? Alos, any recomendations on setting to for optima calls? Thanks in advance.
1. Above the Navigation computer, hanging from the trunk ceiling. Generally, it looks like a black box.
2. In front of the DSP Amplifier. This unit usually is a silver box with a single cable sticking out of the side.
It sounds like you don't have a factory microphone installed, however. Can you shine a flashlight into the grill and check?