<application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>



        <receiver android:name=".BlockCallReceiver" android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.PHONE_STATE" />
                <action android:name="android.intent.action.USER_PRESENT" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </receiver>



    </application>

public class PhoneStateReceiver extends BroadcastReceiver {
    public void onReceive(Context context, Intent intent) {
    // TODO Auto-generated method stub
    String str = intent.getAction();
    if ("android.intent.action.PHONE_STATE".equals(str))
        inComing(context, intent);

    if ("android.intent.action.NEW_OUTGOING_CALL".equals(str))
        outGoing(context, intent);
  }

 private void inComing(Context context, Intent intent){
    String callState = intent.getStringExtra("state");
    if ("RINGING".equals(callState)){
        Log.i(TAG, "RINGING SENDS BUSY");
    }else if ("OFFHOOK".equals(callState)){
        Log.i(TAG, "OFFHOOK SENDS BUSY");
    }else if("IDLE".equals(callState)){
        Log.i(TAG, "IDLE SENDS AVAILABLE");
    }
  }

 private void trueCallerOutgoing(Context context, Intent intent)
  {
    String callState = intent.getStringExtra("state");
    if ("RINGING".equals(callState)){
            Log.i(TAG, "RINGING SENDS BUSY");
    }else if ("OFFHOOK".equals(callState)){
            Log.i(TAG, "OFFHOOK SENDS BUSY");
    }else if("IDLE".equals(callState)){
            Log.i(TAG, "IDLE SENDS AVAILABLE");
    }
  }
}

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

<uses-permission android:name="android.permission.READ_PHONE_STATE" />