Cell broadcast is designed to deliver messages to multiple users in an area. This is notably used by ISPs to send Emergency/Government alerts. Runs at boot time and is also triggered after exiting airplane mode. https://en.wikipedia.org/wiki/Cell_Broadcast https://www.androidcentral.com/amber-alerts-and-android-what-you-need-know https://android.googlesource.com/platform/packages/apps/CellBroadcastReceiver/+/refs/heads/master/src/com/android/cellbroadcastreceiver
Phones target this application