The built-in microphone transmits your voice with high quality?? so family and friends can hear every word without trouble .The max Bluetooth range is about 33ft if there no barrier?? the connection may interrupted by the wall or something else?? this earpiece will lose connection when out of range. Or the Bluetooth clip may not compatible with some mobile phones.</br>Integrated multi-point technology lets you connect two devices at once?? so you can seamlessly switch handsfree between your business and personal phones</br>Bluetooth V4.1 technology provides stable Bluetooth signal?? ensure smooth sound transmission</br>Press the button on the device lets you manage volume?? pause?? forward/back & answer call