And UDP hole-punching has actually gotten much easier. It's baked into the collection of specs that make up WebRTC now, for example. https://tools.ietf.org/html

And UDP hole-punching has actually gotten much easier. It's baked into the collection of specs that make up WebRTC now, for example. https://tools.ietf.org/html/rfc5389 https://tools.ietf.org/html/rfc5389 Mobile networks often don't allow UDP hole punching, and for users behind corporate firewalls, NAT is impossible. But the standards support for "try p2p, then fall back to lightweight relaying of media, then fall back to tunneling inside HTTPS" are really good, now. So I don't really buy that Microsoft switched to centralized media relaying because of changes in deployed network architecture. Possibly the goal is to eventually unify how Skype for Business and "consumer" Skype work. If you are selling a communications tool to enterprise customers, it does make sense to move away from p2p, because enterprise networks are generally locked down in ways that might make the decision to just skip even trying to support p2p defensible. Or maybe it's the lure of building features you can only do on media servers (compositing, various kinds of content analysis including inserting Cortana hooks into every call, etc). Or maybe the speculations about government pressure are correct.