On February 1, 2019, AWS will no longer require IAM users to enter an MFA six-digit code if the IAM user is setup with “An SMS MFA device”. These users will also no longer be provided an SMS code when they sign in. We encourage you to use MFA through a U2F security key, hardware device, or virtual (software-based) MFA device. You can continue using this feature until January 31, 2019.
