Like Telegram, Skype, etc. bind 2 clients behind NAT p2p?

Question

Computer networks

Send the Lord. How do the subjects from the question, and the rest of the dialers, scribblers, connect two clients directly? I don’t know if there is such a thing in Skype, but the cart can connect two people bypassing its servers. I know about TURN, but is there more or less, let's say, an official way, and not such hacks to bypass NAT'a?

Answer 1

And for a long time skype back became p2p? Everything is driven through.
Or stun/turn when needed.

Answer 2

STUN apparently. This is the same "hack" for bypassing NAT. There is another option with UPnP, but in my opinion very few people use it.