Emergency contact
You were listed as an emergency contact in TAP
Someone named you on their TAP Medical ID so that if something happens, they can send you an emergency message from the lock screen. Install TAP and verify your phone and email so that message can land in your TAP Message Center as well as SMS.
What to do
1) Install TAP
Get TAP from Google Play, or sideload the APK if you already use that path.
2) Sign in and verify phone and email
Open TAP, create or sign in to your account, then complete phone and email verification. Lock-screen alerts use your verified phone to find your TAP inbox.
3) Keep TAP on this phone
You will still get carrier SMS even if TAP is closed. Message Center shows the same emergency text the next time you open TAP (or Neverhold with the same account).