It's an audio chat. Allows you to send audio messages after the moderator has given permission.
There are rooms open and all, rooms open only to one's contacts and rooms open only for those who are invited.
There are also room indexes dealing with certain topics.
Many listen to talks of VIP characters.
It is necessary to have a site with a lot of space and a lot of bandwidth.
I think that at least one (or multiples of it) tens of thousands of euros it takes in addition to the technical structure to host such a data flow (server, bandwidth, etc.)