afaik it is more decentralized than Signal, and you can run a server. It uses some block chain crypto network for onion routing or something like that, but to host your own node it seems like you have to buy in. I was reading about it some days ago.

The way they have it set up, they say that the prohibitive cost of buying out the network would prevent anyone from doing so, but I’m sure they’re secretly hoping some government will try to take it over so they can get rich.