Use case info:
The “personal room” with webex is not allways open! It has some kind of “hallway” where visitors have to wait, until I open it up. (If I’m not already there that is 
) It’s my room and mine alone. 
I can configure it to send an email, if someone enters the halway. A kind of door bell …
In delta chat, if I send an invite (the troublesome URL) then I’m redirected directly to my own room - opening it up. There I wait for the other party to arrive. Bingo!
After my partner(s) arrived, I can close the door manualy or after a configured time, so no one can “bomb” our chat in progress.
This works perfectly … but in windows only 