Block all calls programmatically

Requirement:

Block incoming and out going calls.

Steps:

Register a broadcast receiver to monitor calls.

In AndroidManifest.xml file write:

<receiver android:name="MyPhoneReceiver">
    <intent-filter android:priority="100">
        <action android:name="android.intent.action.PHONE_STATE"/>
        <action android:name="android.intent.action.NEW_OUTGOING_CALL"/>
    </intent-filter>
</receiver>

Create a broadcast Receiver to catch the "call" related broadcast.

public class ProcessCall extends BroadcastReceiver { 
 @Override 
 public void onReceive(Context context, Intent intent) { 
  //Create object of Telephony Manager class. 
  TelephonyManager telephony = (TelephonyManager)  context.getSystemService(Context.TELEPHONY_SERVICE); 
  //Assign a phone state listener. 
  CustomPhoneStateListener customPhoneListener = new CustomPhoneStateListener (context); 
  telephony.listen(customPhoneListener, PhoneStateListener.LISTEN_CALL_STATE); 
 } 
} 

Create a custom phone state listener.

import java.lang.reflect.Method; 
import android.content.Context;
import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;
import com.CallLogApp.helper.BlockNumberHelper;
import com.CallLogApp.util.UDF;
import com.android.internal.telephony.ITelephony;
 
 
public class CustomPhoneStateListener extends PhoneStateListener {
 Context context; 
  
 public CustomPhoneStateListener(Context context) { 
  super(); 
  this.context = context; 
 } 
  
 @Override 
 public void onCallStateChanged(int state, String callingNumber) 
 { 
  super.onCallStateChanged(state, callingNumber); 
  switch (state) { 
    case TelephonyManager.CALL_STATE_IDLE: 
    break; 
    case TelephonyManager.CALL_STATE_OFFHOOK: 
    //handle out going call
     endCallIfBlocked(callingNumber); 
    break; 
    case TelephonyManager.CALL_STATE_RINGING: 
    //handle in coming call
     endCallIfBlocked(callingNumber); 
    break; 
    default: 
    break; 
   }  
  } 
 
 private void endCallIfBlocked(String callingNumber) { 
  try { 
 
   // Java reflection to gain access to TelephonyManager's 
   // ITelephony getter 
   TelephonyManager tm = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE); 
   c = Class.forName(tm.getClass().getName()); 
   Method m = c.getDeclaredMethod("getITelephony"); 
   m.setAccessible(true); 
    com.android.internal.telephony.ITelephony telephonyService = (ITelephony) m.invoke(tm);
   telephonyService = (ITelephony) m.invoke(tm); 
   //
    telephonyService.silenceRinger(); 
    telephonyService.endCall(); 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 }
}