Sorry to be anal about this, but I'm not familiar with VOX. So if I'm listening to my music and my passenger is listening to her music, how do I know when she wants to speak to me? Can she just push her intercom button and it overrides my music? If I'm reading the above correctly, I would hear some sort of acoustic sound, then press my MFB to go to intercom mode and speak to my passenger? Thanks in advance for the detailed replies - this may be a better solution than the Scala after all. I particularly like that it is fully waterproof.