I have an 8700g in the US and I have noticed a few times that the radio has gone off by itself (unless somehow I managed to hit a wrong key, but I doubt it). For example, I had the phone on, put it in my holster and in my pocket and went in to shop, when I came out the radio was off. There is NO BT involved (i.e. don't use a headphone).
I am sort of waiting to see how often this behavior recurs and if any other people on this board have similar experiences before going further.
Of course it COULD be I turned it off in the store and forgot about it....I AM getting pretty old, after all.