Blackberry - call method by interacting with system dialog

Question

When a system missed call popup screen appears I want to call a method by clicking on VIEW button on that screen.
Actually when I click on the View button I am trying to close a thread by calling a stopThread() method of my application. But I am unable to get the activeScreen object. I am already tried with the following code but it returns the object of net.rim.device.apps.internal.phone.PhoneAppScreen. This was the codes which I tried to use but not able to access the required object.

1) Screen activeScreen = UiApplication.getUiApplication().getActiveScreen();

2) Screen activeScreen = Ui.getUiEngine().getActiveScreen();

Please reply if someone realy know about it. Thank you