The system must offer secure out of band authenticators, such as push
Clear text options such as SMS, mailing or PSTN may be offered but should
not be the default option.
Secure out of band authenticators are physical devices that can communicate
with an authentication verifier over a secure secondary channel.
They serve as an additional security measure for identity assertion during
authentication processes or sensitive transactions.
Systems should offer at least one out of band authenticator and the default
option should not be a clear text one.