If you want a system that is less likely to be controlled or you just want a backup route to stay connected in case other media gets taken off, try Delta Chat. I'm not affiliated in any way, it looks like a chat program, like telegram, but it is email based so no single server to target and it's open source with apps for the iphone, android, linux, windows and mac. You only need an email address to use delta chat and you don't have to use delta chat to be on a group. Read more about it at https://delta.chat/en/