Android Check if call forwarding is activated

Question

I am building a call forwarding application and have used the **21*xxxxxx# ussd code to activate call fowarding using ACTION_CALL Intent. But I have not found a solution to

Answer 1

 TelephonyManager manager = (TelephonyManager)    
 this.getSystemService(TELEPHONY_SERVICE);     
 manager.listen(new MyPhoneStateListener(), 
 PhoneStateListener.LISTEN_CALL_FORWARDING_INDICATOR ); 

 class MyPhoneStateListener extends PhoneStateListener{  

  @Override
    public void onCallForwardingIndicatorChanged(boolean cfi) {
      Log.i(TAG,"onCallForwardingIndicatorChanged  CFI ="+cfi);

         preferences.edit().putBoolean("CALL_FORWARD_ACTIVE", cfi).commit();
        super.onCallForwardingIndicatorChanged(cfi);
    }

}

if cfi returns true that means set call forward success