As long as the "Participate" button is displayed in the chat, you can still join the conference. After the conference has opened, there is still 2 hours to join the conference via chat. 

This means above all if you as a teacher are in a group with students in a conference that should be finished before the end of the 2 hours and you want to make sure that nobody is in the video conference without your presence , we recommend the following procedure :

1. While you are in the video conference, click on the "Close conference" button in the Sdui chat. Otherwise, students could continue to join the conference after they leave the conference room.

2. In the conference you can now kick the remaining participants out of the conference one by one. As the moderator of the conference, you will find the button "throw out" via the three dots in the participant's tile.

You can then see in Sdui how many people took part in the conference in total.