I want to set up a video calling app, does anyone have any tips?

I want to create an app for personal use that makes video calls, I already made the call app but I can’t fit it into the project to open video, can anyone give me tips, it’s a calling system using a cell phone number but that When the call is answered, it also opens the video.

Hello,
You can look into this : Video call [FREE]: Using Agora.io