In my opinion, that sounds like precisely the sort of system that should not offer an SMS fallback unless the goal is to create a false sense of security in the

In my opinion, that sounds like precisely the sort of system that should not offer an SMS fallback unless the goal is to create a false sense of security in the user. But YMMV, I don't generally need to access my online banking applications when I don't have useful internet access. I tend to use TOTP for systems where I'm concerned about offline usage. But again, YMMV.