Discord is pretty good for gaming communities. I've also seen some discord servers for selling shit like crypters and other things to bypass Anti Virus. I've also heard of teen dating servers which sounds creepy as fuck
Teamspeak is also good for gaming communities and has plugins like gSpeak for Garry's Mod and TFR for Arma 2/3 which improves voice quality but servers are expensive. I haven't used teamspeak in a while though. The last time I used it was for this old Arma 2 Takistan Server
Skype.. Who uses skype?
EDIT: Correct me if I'm wrong but I think you have to pay for the Teamspeak IOS app which is retarded