If you can silently pair to a phone, you can make the phone dial whatever number you want. Recently found this out when connecting the serial terminal to an earbud for repair (it wouldn't auto-connect to the other earbud).
How would you reliably unlock the phone and get to the dialer app? Given how varied home screen layouts are, even an unlocked phone might be hard to attack this way
That's not what I mean. You can instruct the phone - over bluetooth, within the bluetooth functionality - to dial a number. No lock screen or dial app to access.
You can always reset by tapping the home button or swiping the most recent app away or so, so you can try various UI layouts until one works. Most Androids have a settings button in the notification area and then you can find the installed apps, search for the dialer, etc. Don't need to assume a certain homescreen location.
