With our new hosting we have the possibility to open a TeamSpeak3 server for free on the same computer as our UrT server but it can (not sure at all) create a bit of lag on the server. Do you think it's a good idea ? Vote !
I also have Mumble, and it's a good speaking software, but I don't know if more players use mumble or more players use TS3 so I can install a TS3 server and a Mumble Server on the hosting to try
Any will do the job. Some say that Mumble is much better when paired with urt, other say TS3 has a better sound quality, so your call. But more people use TS3, so I would say that makes it a smarter choice.