I contacted support, who promise a 24 hr response, to ask if my unit may be faulty or is it just how they are, and not fit for purpose. Considering it has been 120 hours and no response, I can only suppose the seller is aware of the microphone issue, and the microphone is not fit for phone calls.
The issue is that the other party cannot hear very well. I have for many years been using a $24 Plantronics single ear bluetooth mic and it has performed great. On my first two calls with the VAVA MOOV 28, the other party, unprompted, both commented straight away that my volume was very quiet compared to our normal conversations - they were alone in quiet rooms, one on an Android mobile, the other IOS. On the third call the other party was at an airport on an IOS mobile, and they could not hear me well enough to actually have a conversation, and I had to call back using my old ear piece.
I have since noticed that other models of a similar design that the seller has, will have the mic on the outer side or front of the control unit when wearing. With the VAVA MOOV 28 the microphone is on the inside. This makes the microphone face 45 degrees to the rear, and the microphone is then positioned 10mm or so from my skin. Perhaps this microphone positioning is the issue? Or perhaps the mic quality itself, or simply poor circuit design.
If you don't require a microphone for mobile calls, Skype or other voice applications, and you can get this for half price, it is probably a good buy. If not, look elsewhere.
The sound quality from the earpieces is good, though not what you would call full range. As is often the case, bass is emphasised, and the upper bottom end can become somewhat muddy. The unit functioned in apt-X mode with a modern Android device, and video had synchronised audio. The bluetooth controls worked fine, and I had it simultaneously paired to two devices. The range was excellent and comparable to the best I have achieved in my environment with the same classed devices.
It gets 2 stars because it doesn't fully work( and Amazon will not allow 2.5 which I feel it deserves as a package, albeit with the poor mic). The lack of a response from the seller is disappointing, especially considering their claims to the contrary. I will be returning the VAVA MOOV 28 and it is a shame about the poor microphone, or I would have been happy with the discounted price of $28 that I paid.