@Gargron I really like XMPP. I use https://jmp.chat for their SMS/MMS/PSTN transport and I have an IRC transport. On top of that there's a bifrost instance on matrix.org. With those I can connect to Matrix MUCs, IRC channels, and MMS groups all from the comfort of XMPP. I also have most of my friends and family over on XMPP thanks to Quicksy for OMEMO E2EE communication.