If you have an old or spare smartphone that is no longer a 'phone' it can still be used for WiFi and bluetooth for connected devices. I have my old smartphone (no SIM card) that I now use for streaming Spotify in the rig. If you have other systems like a TPMS or Leveling system that has an app and can run on a smartphone with bluetooth it is a great use for an old Smartphone that is no longer a phone.