Do I need a front end?

I have deployed the server(https://openvidu.io/docs/deployment/deploying-ubuntu/) on Ubuntu machine. I’m getting a page where I can test after allowing camera and mic. Do I need a front end to make a video call session work?

One peer is Android device and the other is from the web.

What do you mean with “do I need a frontend”? Well, if you want to develop an application, you will for sure need a frontend side. OpenVidu doesn’t make sense without a frontend.