I'm struggling to see the USP here. Skype was never a viable option, hence never mentioned. Discord which works on PC or Mobile, provides an activity status for firestorm https://wiki.firestormviewer.org/floater_discord so you know who is inworld, you add a voice channel and users can choose to access it so no interruptions. Unless I'm missing something, it offers the same features Discord does for free with unlimited channels and users, but this service costs $10 - $30 euros pa with limited users and channels? Now if you manage to find a replacement for Vivox before it disappears then I might be interested.

Hello everyone then Virtualife voice hosting and a telephony system you can connect either from the PC,
I choose to connect from your mobile,
even if you are not in the game and keep in touch with your friends.
Very light as it has no other function than the voice.
It is true that there are other applications such as Skype or Discord etc. around,
but they are heavier applications that vary in many things.
Most important example if you make a skype call
in the group you call all participants of the group,
instead with our system you easily connect to the group and as someone enters the game where you are,
he will do the same thing and you will talk, thus not disturbing others.

Does this provide the ability to utilize/replace slvoice.exe and configured in opensim.ini as an alternate to vivox and thus enable the inbuilt firestorm voice features or is it external of opensim operating a little like discord and other free group chat systems?