title: Best way to link a FCM token to a device?
body: <p>I'm making a server that sends messages using FCM to clients depending on what happens (temperature and/or humidity change, a door is opened, etc.).</p>
  
  <p>But if the token can change, how can I keep track of the device to send messages to the correct one (w/o using a login system)?</p>
  
  <p>I was thinking to link the token to the sim iccid in a database, is this correct?</p>