After have searched since more hour, I've found this about my problem (Stay on my activity when dialing) but a negative answer.
My project consist to help a handicap (deaf people). I want to launch a call since my app and go back to my app (like return button) to show voice data.
Currently, I just need to do system like return button and I ask you in order to get help !
To call a number :
Intent dial = new Intent(Intent.ACTION_CALL, Uri.parse("tel:" + "666-666-666"));
dial.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_NO_USER_ACTION);
startActivity(dial);
And I've a PhoneStateListener to know the state of the CALL.
The link I've shared's the only one I've found to this subject.
Thanks for reading.