Its free, its designed for gamers and its like skype in that you can have friends on a list that you can see who is on line and who is not but yet you dont have to be in a TS server or pay for a TS server. Anyone can make a channel and invite anyone else or give rights to someone else to invite someone. Means making clans and friends from Rust very easy and simple to keep in touch with them.
Its a great system, free and kind of seems to combine all the best bits from things like Skype and TS that gamers want. Well worth a look