It's probably also related to them not wanting to make Signal selfhostable. The server (and client) code is open source[0] but is reliant on an external SMS ser

It's probably also related to them not wanting to make Signal selfhostable. The server (and client) code is open source[0] but is reliant on an external SMS service to be self-deployed (as well as AWS for file storage, GCM and APN for push notifs but those aren't nearly as much of a barrier; AWS has numerous FOSS reimplementations while for GCM you can use ntfy), something which Signal devs have stated they don't want to happen (since providing libsignal implementations is, as far as I understand, part of how Signal makes money). SMS is afaik the only real barrier they have to preventing that. [0]: As in, AGPL and effectively a source dump with no instructions.