MFA not working for me with Authenticator app on current phone and Bad Reputation on SMS

Hello @Raja PothurajuI see that you've been tagged about this problem by other people and hope that you can help.

I am the only user, global admin, for a microsoft account where I have previously installed an Authenticator, most likely on a phone I don't have anymore.

I can't set up authenticator on my current phone therefore and when I try to send autheniticate myself via SMS I get the following error:

Error Code: 399287

Request Id: ccea322e-d1f0-49cf-9042-8e777b6a1a00

Correlation Id: a0dd6000-d57d-cb36-b577-83819c3a2f96

Timestamp: 2025-09-29T17:16:36Z

I see that this due to a 'Bad Reputation' on my phone number which I hope that can be resolved.

Stuart