“If you’re looking for an open source Skype alternative that prioritizes the privacy of its users, then Jami – which used to be known as Ring – is the one to go for.
Jami has a professional-looking design and is available for a wide range of platforms. Unlike other Skype alternatives, calls using Jami are direct between users, so it doesn’t use servers to handle calls.
This gives you even greater privacy, as the decentralized nature of Jami means your calls are only between you and the person you’re calling – no one else can see (or hear).
Jami has got a good selection of features, such as HD video calling, instant messaging, voice messaging, and file sharing. It’s also totally free to use.” – https://www.techradar.com/best/best-alternatives-to-skype