Preauthentication and self-rescue
    BlackBerry 2FA
            Preauthentication and self-rescue are features that allow users to authenticate to your
            organization’s resources for a predetermined period with only a single factor. These
            features are enabled and configured independently.Preauthentication should be used when the user expects to have no device
            access or no network coverage for a short period of time (for example, when they are on
            an airplane). Users can request Preauthentication from the their device, or
            administrators can enable it through the 
BlackBerry UEM
            management console. BlackBerry
 recommends using the software OTP feature instead whenever
            possible because it retains full two-factor security, even though it is less
            user-friendly.Self-rescue should be used when a user has lost their device or has no device access for
            a longer period of time such as a day or more (for example, the user lost their device
            and is waiting for a replacement). Users can access the self-rescue feature from 
BlackBerry UEM Self-Service
, which means
            that it can only be enabled if the user is connected to the organization’s network.