@OpojOJirYAlG, You just reminded me of another thread where I talked about the Google Voice…
If you don’t want to follow the link to the GitHub feature request, I was asking Nextcloud to find a way to do privately through their system what Google did with the Voice project. Apparently, they (Nextcloud and Purism) seem to already be on it.
Because I switched from T-Mobile to Googles Project fi for my mobile phone services, I’m currently not allowed to use the Voice system anymore with that Gmail ID or the main number that I got through Google Voice.
In my private Nextcloud instance, I’m behind a residential FiOS connection and the Nextcloud Talk subsystem lets us enjoy video-conferencing on Android and iOS (plus all computers) with better quality than the Google Hangouts provided (I’ve experienced both the free and the paid versions of Hangouts), and our video is encrypted via our own free LetsEncrypt https keys. The NC Talk software was initially the Spreed project’s software. I’m not sure if Spreed let NC have it and now Spreed just sells hardware that runs it, or what. I just know it works for me; voice calls, video calls, text, file sharing, and if at a desktop/laptop you can have screen-sharing too.