This project detects incoming call and once incoming call is recieved it shows popup message but unfortunately it can't get phone number.
It uses BroadcastReceiver for detect phone state and requires READ_PHONE_STATE permission,
When call is recieved onReceive method is called with android.intent.action.PHONE_STATE action
then it uses TelephonyManager class for set listener on call state and when state becomes CALL_STATE_RINGING
that means call is recieved and the phone is ringing,
at that moment it opens Activity as popup alert using Theme.AppCompat.Dialog.Alert theme and singleInstance launchMode for launch independent of others activities.