Sole global admin locked out — MFA SMS blocked with error code 399287

I am the only global administrator for our Microsoft 365 tenant (domain: fiskher.no). I am unable to sign in because all available MFA methods fail:

• SMS verification to my registered phone number fails with error code 399287 ("Sorry, we're having trouble verifying your account")
• Microsoft Authenticator is no longer registered on my device, and I cannot re-register it because that requires signing in first

Error details:

• Error Code: 399287

I understand this error means my phone number has been flagged by the PhoneReputation service. Since I am the sole admin, no one else can reset my MFA. Could the engineering team please unblock MFA for my account from the backend? I can provide the account UPN, tenant ID and phone number via private message, and I can prove domain ownership via DNS if needed.