It is because you get a real phone number unlike mysudo/jmp that provide you with a VOIP number, which fails most SMS based verification.

strach z promeškání

Actually, email is optional. But the lack of information makes my imagination go wild.

Looks like they only encrypt before storage. Outgoing messages are unencrypted, incoming too, so while SMS Providers don't protect you or your messages, they also don't protect them I would assume.

The only thing this provides is pseudonymity against the SMS providers, but with access to messages, that can quickly be deanonymised.

Also, they say that they protect against sim swaps, but how exactly, it seems they are at the same mercy of the SMS providers that we would be if we used our own sims.

Seems expensive for a false sense of security. Prove me wrong.

👀