Whenever it has to fallback to SMS.

I mean there’s really no other realistic way to enable a single app to utilize two very different communication “protocols” (in quotes, because SMS is only nominally a protocol).

I’ve always though iMessage was the approach to getting away from crappy SMS.

So when Signal did the same, I was very optimistic. It removed a barrier to entry for users by supporting SMS plus an encrypted method for connections that had Signal. And you could enable it to add a signature saying something like “Sent from Signal, this could be an encrypted conversation if you download Signal” or something like that. That was a great idea.

(weird, not sure why these are two comments and it looks like I replied to myself)