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What to do if…
your messaging app shows your account is linked to a new companion device you do not recognise

Short answer

Assume someone has access: immediately unlink/log out the unknown companion device in the app, then secure the underlying account (new password + two-factor authentication) from a device you trust.

Do not do these things

  • Don’t message the unknown device/user, negotiate, or “see what they do.”
  • Don’t approve any prompts you didn’t initiate (QR pairing, login approvals, “new device” confirmations).
  • Don’t share verification codes or screenshots with anyone who contacted you first.
  • Don’t change random settings before you’ve removed the linked device(s).
  • Don’t reuse an old password or a minor variation.

What to do now

  1. Pause and use a safer setup. If you’re on public Wi-Fi, switch to mobile data or a trusted network before making changes.
  2. Unlink/remove the unknown companion device immediately (inside the messaging app).
    • Look for Linked devices / Companion devices / Device pairing / Sessions and log out/remove anything you don’t recognize.
  3. Save quick proof for yourself. Take screenshots of the linked device list (device names, timestamps, “last active”). This is useful if support asks for details.
  4. Lock down the account behind the messaging app (do this from a clean device).
    • Change the password for the account used by the messaging app (or your Apple/Google account if that’s what it relies on).
    • Turn on two-factor authentication (2FA).
    • In the account security area, sign out of other devices/sessions you don’t recognize (often under “Your devices” / “Manage devices”).
  5. If you can’t remove the device (or it comes back), escalate immediately. Use the app/provider’s official website and complete their account recovery/support process.
  6. Protect your email account (the reset point). Check for:
    • New forwarding, filters/rules, unfamiliar recovery email/phone, or unknown trusted devices.
  7. Watch for phone-number takeover (SIM swap) signs.
    • If you lost service unexpectedly, got carrier alerts about SIM changes, or can’t receive calls/texts, contact your mobile carrier using a known official number and ask them to check for unauthorized SIM changes/port-outs and add extra account security where available.
  8. Warn people who might be harmed by impersonation. Using a different channel if possible, tell key contacts/group admins: “My messaging account may have been accessed. Don’t click links or act on unusual requests from me.”
  9. If there’s fraud, threats, or identity misuse, report it using official sites you type in yourself.
    • IC3 (FBI) is a common reporting route for cyber-enabled crime/fraud: go directly to ic3.gov or complaint.ic3.gov.
    • If personal identity info is being misused (or you’re not sure), IdentityTheft.gov (FTC) can guide immediate recovery steps.

What can wait

  • You don’t need to figure out exactly how it happened before you act.
  • You don’t need to publicly post about it or confront anyone.
  • You don’t need to factory-reset your phone unless the account keeps relinking or you later find malware.

Important reassurance

Seeing an unknown companion device is alarming, but quick unlinking plus 2FA and sign-out of other sessions often shuts this down fast. You’re not overreacting by treating it seriously.

Scope note

These are first steps to stop access and reduce immediate harm. If the unknown device reappears after removal, escalate to the provider’s account recovery/support flow and consider a device security check.

Important note

This is general information, not legal advice or a technical forensic investigation guide. If you’re being targeted, stalked, or repeatedly compromised, consider involving support services and making a formal report.

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