Unregistered Multi-factor Authentication means that it is possible to require Unregistered SMTP or Unregistered SMS as the second factor authentication method for unregistered users returned from a SAML method or an OpenID Connect method.
While normally with Unregistered SMTP or SMS end users need to enter their email address or mobile phone number, in multi-factor authentication that information is passed as method attributes from the OpenID Connect or SAML method.
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