How to develop SDK + backend for video communication?

Question

Android

Hello, is Webrtc a free video conferencing SDK? And then it connects to paid video servers like Twillio via API? Are there such projects like Twillio only free, or can you give information on how to implement or what you need to implement to create your own such server that will work with the Webrtc SDK for live broadcasting in the application and video communication. And tell me what all this is called, for example, if you make your own video communication, first you write your SDK, then where does it connect to, to the server part (if so, what to implement there)? If you order a freelancer to implement it, you will need to explain what needs to be implemented.
PS I'm still a noob in this, explain to anyone it's not difficult. At the moment, video communication is implemented on Twillio, in the future I want to make a free implementation of video communication and implement live broadcast in the application

Answer 1

Why not go for webrtc. In terms of time, this is 3 months of work, native clients are of course aerobatics

Answer 2

Isn't that it? https://habr.com/en/post/198632/