Fix Teams Mobile Login

Microsoft Teams refuses to sign in on my Windows Mobile handset and only returns “Authentication failed.” The same credentials work perfectly on desktop and web, so the issue is isolated to the phone. I’m not sure whether the device received a recent OS update, and I also don’t know if any MFA requirement is silently blocking the session.

Your job is to pinpoint the exact cause—whether it’s cached tokens on the device, an outdated Authenticator configuration, a conditional-access rule in Azure AD, or something else entirely—and restore normal sign-in. I can provide remote access or join a screen-sharing session so you can collect logs, review Intune/Endpoint Manager settings if present, and run any diagnostics you need.

Acceptance: I enter my usual credentials on the handset and land on the Teams home screen without errors.

Deliverables
• Clear step-by-step outline of the investigative actions you’ll take before you begin
• Live guidance or remote execution of the fix until the device signs in successfully
• A concise report that lists the root cause, exact changes made (registry edits, policy tweaks, credential resets, etc.), and preventive recommendations so the problem does not recur