Same problem here I have a logitech 650 usb headset for teleconferencing with my laptop (BT meetme dolby service). Samsung claims, the galaxy S5 has a full OTG port (usb host port for mobile) But for audio, only playback on the USB is supported, not the microphone, so i need a second headset, using the 3.5mm plug or bluetooth, to use the BT meetme dolby app on the S5.