We purchased this head set to communicate via voice activation (VOX) between two talk about T600 radios.  We tried multiple approaches to get this to work but in the end, we could only get one set to work on VOX and the other had to be push to talk PTT.  Further, it is not at all tolerant of background noise and the VOX locks out the other radio when background noise is present.  Going to try the much more expensive EarTech Ultralight next.