Voyst is not only focused on communication but location-based services. So I like that the voice bubble in the middle of the "o"... might also be seen as a pin on a map.
In reviewing your concepts with the rest of the team one thing that we all agree on... the voice bubble / pin concept is unique and a good representation of our company. Well done.
One thing we are struggling with however is that the logo might be a little to playful for our liking. I am not sure what it is? Font style? Bevels/Shadows? Ultimately we want a logo that is simple, memorable, sophisticated and timeless. I think you have delivered on 1&2. If you are open to trying a few more concepts I would like to see more 3&4.
Actually I don't think my concept is playful. Anyway I try to do some new designs with different font, maybe that makes them better. Thx for your comment.