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I recently installed a SONY MEX 4200 BT car stereo, which allows bluetooth connectivity and has built-in mic for handsfree function. The problem I'm facing is that while my NEXUS 6p is connected via bluetooth to the car stereo and I accept a call, nothing is heard from the speakers. Making a call while connected works flawlessly, so does playing music from my NEXUS. My wife has a HUAWEI P9 lite, and has no problem making or accepting calls through the car stereo. I've tried the usual suggestions to solving BT connectivity issues, but the problem persists. Any suggestions?