Hi @Jezeski, Troy J (OIT) , I'm sorry you're having this issue! Unfortunately, there's not much we can do on our end as you can't whitelist phone numbers for MFA. The number's reputation comes from their phone carrier. You would have to ask the user to contact their carrier to resolve the reputation issue. The only other solution would be to use a different MFA method such as Authenticator.
Please let me know if you have any questions and I can help you further.
If this answer helps you please mark "Accept Answer" so other users can reference it.
Thank you,
James