Forgot to mention: Tested via google+ and hangouts with above mentioned android version. No FB acccount or messenger on mine to test that app so cannot speak to it but it seems the method of mitigating this attack is built in to Android.
There's yet another intent for dialling emergency numbers without prompt, which is reserved for system use -- non-system apps can only dial emergency numbers indirectly using ACTION_DIAL.
[0]: https://developer.android.com/reference/android/content/Inte... [1]: https://developer.android.com/reference/android/content/Inte...