An SMS payment system doesn't seem possible. Just end-to-end encryption for SMS will be much be bigger than a Facebook app. Without encryption consumers will be conducting wire transfers over cleartext to the merchant.
They are used a lot in countries with dysfunctional banking systems. They aren't encrypted, they use the fact that you're sending a text from your phone to validate that it's you.
They are used a lot in countries with dysfunctional banking systems. They aren't encrypted, they use the fact that you're sending a text from your phone to validate that it's you.