All Skype and Facebook Messenger both with SMS support have same issues as Signal, centralized and from even worse big corps. AFAIK there is no IM with SMS support, I wished someone made Matrix client with SMS, it would be insta replacement for my dedicated SMS app and I need SMS support pretty much just to receive verification codes, delivery information etc and once in a few months writing SMS to kidnergarten my sick kid won't come, nobody use and will use RCS, so Signal can keep that BS excuse.