Comment by mdnahas

It varies by car. For my Honda, I believe disconnecting the antenna is enough. I looked at a Toyota and the antenna is shared. To disable the phone-home you had to disconnect a box … but that’s difficult. The box is also designed to call 911 or 999 emergency services and is connected to the microphone and one of the speakers. You have to rewire those if you want to use the microphone with your cellphone or play any stereo sound. Do your research before buying or disconnecting things.