WhisperSystems doomed Signal as an SMS replacement when they dropped encrypted SMS support. Now it's just another instant messenger. Big whoop, I had OTR encryption a decade ago (with more contacts, too - it's a lot easier to say to a friend "install this OTR plugin" than "switch to this IM network/app"). I use SilenceIM.

I only use it as an SMS replacement.

Really, as long as you have mobile data, there's no difference between supporting SMS encryption and not - you can only talk encrypted to other Signal users anyway, and other Signal users will get your non-SMS-routed encrypted message just fine.

The use case for Signal-encrypted-SMS is continuing to send encrypted while you have no IP connectivity, but thankfully that is becoming a rarer corner-case. The last time I had SMS but no IP was on a cruise ship.

Happens all the time for me. Pretty much anywhere in the US, I'd bet there's a spot within 50 miles where all you have is cell coverage.

Ahh, I was not aware of that, in light of that it seems like dropping encrypted SMS support was premature. (Here I don't think there's any places with non-data coverage, though there is now some of the opposite - places with no circuit-switched voice coverage, voice there is only through VoLTE).

Also note that as it stands encrypted SMS is technically superior. This is Moxie's comment on GCM-free Signal:

> I expect it to have high battery consumption and an unreliable user experience, but would be fine with it if it comes with a warning and only runs in the absence of play services

You don't get high battery consumption, or unreliable user experience, or a requirement for Play Services with pure SMS encryption.

SMS encryption is actually quite a tricksy problem. TextSecure's entire purpose (over bog standard IM OTR) was to solve it, providing individual message-level forward secrecy. This is why it's so perplexing to me that they dropped it (I understand that part of the reason is that iOS simply does not allow it)

https://whispersystems.org/blog/advanced-ratcheting/