Android listen for Incoming and Outgoing calls and block calls automatically in android using java reflection

First of all create a new aidl directory, and add ITelephony.aidl.
ITelephony.aidl file should be like this. Its package name must be same as below.

package com.android.internal.telephony; 

interface ITelephony {

 
   boolean endCall();
    void answerRingingCall();
     void silenceRinger();
 }

Create a new class named PhoneCallReceiver add Add these lines in Manifest.xml

<receiver android:name=".PhoneCallReceiver">

<intent-filter><action android:name="android.intent.action.PHONE_STATE"/></intent-filter>

</receiver>

If you want to enable/disable this broadcast receiver. You can add following code inActivity from where you want to start/stop this call blocking functionality.
extends PhoneCallReceiver class from BroadCastReceiver and implement onReceive method,onReceive method will be called whenever Phone_STATE will be changed which we added as action in intent-filter in manifest file

public void onReceive(Context context, Intent intent) {

    Log.v(TAG, "Receving....");    telephony = (TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE);


If statement will be true if there is Incoming Call, if you want to block Outgoing calls
add this code in else body which is below. 

if(intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(TelephonyManager.EXTRA_STATE_RINGING)) {

You can get Caller number using below line of code.
      caller_number = intent.getStringExtra("incoming_number");
       
 try {
           Class c = Class.forName(telephony.getClass().getName()); 
           Method m = c.getDeclaredMethod("getITelephony");
           m.setAccessible(true);
           telephonyService = (ITelephony) m.invoke(telephony);
           telephonyService.endCall();
           Log.d("CallBlocked", "CallBlocked");
           
        }
 catch (Exception e) {
            e.printStackTrace();      
  }

    } else {

        If you want to block Outgoing calls add the above code here...
    }
}