They all have servers you can download and host yourself from your own PC if you're willing to follow a few guides to set this up correctly, I run my own ventrilo server for my friends, it uses hardly any bandwidth or CPU resources.
you're a little wrong. they don't have a server and they are not responsible for the quality and connection speed!
but otherwise everything is OK, and one more .. they hasn't rank in conversation, that is full of cereal, when all start speaking - happend chaos.
and in MyteamVoise everything else! there has multilevel system is designed - it makes the game very effective and convenient for everyone