Reject a call wthout a ring

Question

I'm trying to reject incoming calls without even getting a single ring to the calling person. I am trying to reject the calls by this code but it rejects with one ring.

 public boolean killCall(Context context) {
    try {
        // Get the boring old TelephonyManager
        TelephonyManager telephonyManager =
                (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);

        // Get the getITelephony() method
        Class classTelephony = Class.forName(telephonyManager.getClass().getName());
        Method methodGetITelephony = classTelephony.getDeclaredMethod("getITelephony");

        // Ignore that the method is supposed to be private
        methodGetITelephony.setAccessible(true);

        // Invoke getITelephony() to get the ITelephony interface
        Object telephonyInterface = methodGetITelephony.invoke(telephonyManager);

        // Get the endCall method from ITelephony
        Class telephonyInterfaceClass =
                Class.forName(telephonyInterface.getClass().getName());
        Method methodEndCall = telephonyInterfaceClass.getDeclaredMethod("endCall");
        methodEndCall.setAccessible(true);

        // Invoke endCall()
        methodEndCall.invoke(telephonyInterface);

    } catch (Exception ex) { // Many things can go wrong with reflection calls

        return false;
    }
    return true;
}

i call killCall(Context context) in public void onReceive(Context context, Intent intent) of a BroadcastReceiver. i set CALL_PHONE and READ_PHONE_STATE permission for my app and here is the code for <receiver/> in Manifest.xml

    <receiver
        android:name=".PhoneCallReciever"
        android:enabled="true"
        android:exported="true"
        >
        <intent-filter android:priority="999">
            <action android:name="android.intent.action.PHONE_STATE" />
        </intent-filter>
    </receiver>

Please help me.