This is a simple and secure decentralized messenger that does not use identities. Instead, you create addresses for different channels which you can dispose of. This video explains it well. It supports calls and has a desktop interface as well.
I have setup a server to further decentralize the network. After you install the app, you can go into settings and add the below servers. You can use the default setup servers, but using these spreads the load and makes the network more resilient.