WhoCalled is the easiest way to instantly search on whocalled.us! This app only responds when the incoming phone number is NOT in your phonebook. After declining the unknown number, a notification will appear in your notification bar. Simply click the notification and it will search whocalled.us, showing the most popular answer! Permission explanations: READ_PHONE_STATE: to know when call is over. INTERNET: to lookup who the caller is. READ_CONTACTS: to filter out known contacts.