In most radio contexts it's used for doing a debug log... in case of a hard lock. If you do it on an Android device (depending on settings), it generates an err

In most radio contexts it's used for doing a debug log... in case of a hard lock. If you do it on an Android device (depending on settings), it generates an error log and memory dump then cuts power to the chip. It's an old carry-over from radio testing (Former RF Validation Engineer here)