Telegram bypasses Lufthansa inflight WiFi Paywall - how?

Lufthansa offers an inflight WiFi service called FlyNet. The service is not free, and I've never paid for it. What I did find interesting that somehow the Telegram instant messenger manages to pass the paywall.

If you are connected to the onboard WiFi network, Telegram messages go through. Years ago Skype had a reputation of being able to work behind restictive firewalls, which was nice to stay in touch behind corporate firewalls. In this case Skype couldn't access the network, maybe they no longer want to.

I'm not a networking expert, so I don't know how it works - you can use Telegram without cost in air. Out of curiosity I did capture some video which might help someone try to figure out. Maybe it's just an opening in the firewall for some reason, or maybe using DNS or some other way to access the internet?

How does this work? You tell me:

-- Jani Tarvainen, 2017/12/12