base don what I read so far, there is currently no handsfree set where the TEL button does much more than answering the call. And this only works with one of the (three?) OEM Bluetooth handsfree sets. You can get an aftermarket handsfree kit, connect it to the RNS-E to hear the voice through the build-in speakers and mute the RNS-E during a call, but that's as much as you can get...