Have experience using it as a VoIP app. The main issue with it, is that there's constant regressions, with no real stable version.

For example if a new Android device comes out you can run into issues regarding gain and echoing, they also maintain a list of pecular devices which don't strictly adhere to standards (Mostly Samsung devices). So you end up having to upgrade to a later version. Which ends up causing regressions in many other devices which previously had no issues.

I am ofcourse talking about Google's WebRTC. The best thing to a stable version, is the commit hash used in chrome, but they have just as many regressions as any other version. Building it is also a bit of a pain, although no where near as bad as it used to be, but once it's set up it does the job quite well.