How to unblock video calls
A call in class established automatically, you need to give your browser access to your camera and microphone to be sure that the interlocutor hears and sees you. You will see a browser request on the left top side of the screen, be sure to click "Allow". If access is not open, in the videocall window, you will see a link to this instruction.
If the browser request for access to your camera and microphone does not appear, it means you denied access early. You can check it in content settings. Copy and go to the following URL: chrome://settings/content
Scroll down to the sections "Microphone" and "Camera", make sure you select "Ask me when a site tries to access the microphone / camera" and click "Manage exceptions"
Find vimbox.skyeng.ru:433 in the list, If "Block" selected, remove this line, reload the VimBox page and don’t forget to click "Allow" on the browser request next time.