[mothepro]

Not necessarily, TURN servers should only be required for strict NAT. It seems that 92%* for connections are not behind strict NATs.

*https://developers.google.com/talk/libjingle/important_conce...

[bkanber]

STUN fails under symmetric NAT, not strict NAT. That google document makes no citations of that 92% figure, but I assume that's for desktop traffic only. Pretty much all mobile/cellular connections would require TURN too.

[cma]

I haven't found Verizon or AT&T to need TURN, but maybe clients on them would if connecting to each other.

[FR10]

In my tests with 10 people 5 needed TURN, ISPs in my country are really something special.