About Matrix Matrix is an open protocol for decentralised, secure communications.
Matrix Manifesto We believe:
People should have full control over their own communication. People should not be locked into centralised communication silos, but instead be free to pick who they choose to host their communication without limiting who they can reach. The ability to converse securely and privately is a basic human right. Communication should be available to everyone as a free and open, unencumbered, standard and global network.
The free open public jitsi do get bogged down now and then. And based on where you are located, can be far away. I run my own jitsi instance, so do not have that problem.
Also element is working on a built in call function that do not use jitsi. But i have not tested it. https://element.io/blog/element-call-beta-3/