A:Answer The microphone on your smartphone is TOO FAR away from your mouth *and* that same mic is TOO CLOSE to a car speaker *and/or* you have the speaker VOLUME very loud for a hands-free call. This happened on a call with my family member, but after I relocated the phone (& its holder, low by my knee) to be closer to my voice (higher by my hand) and further from the speaker that was close to the phone (& my knee), while *also* turning down the volume slightly...everything was FIXED and worked ideally!
When the phone's mic is far away, your caller cannot hear you very well - just like when you use it away from your car. The delay "feedback" comes from the caller hearing their own voice THRU your car's speaker and INTO your phone's mic, since any voice/sound takes longer to travel thru a phone to a distant speaker via a network (re: speed of sound).
*NOTE: Some users mistakenly think that a microphone is located on the transmitter/charger itself. However, this product only utilizes Bluetooth for outputting/broadcasting the phone's audio (calls, music, etc.) to your car's speakers.
