Error code D0100 means that the phone number you entered cannot be used for multi-factor authentication (MFA).
Our process assigns a score to every phone number used for MFA and your phone number was assigned score that is too high to be accepted.
Scores are assigned for reasons unique to each user and their phone history, so unfortunately we are unable to provide details on exactly why this score was applied to your phone number. (High scores are common with new phone numbers.)
Please use a different phone number for MFA, or select a different MFA option.