How do I enable call waiting notification when I am calling another person?

When I used my previous phone, when I am calling someone, I used to get a notification if the party that I am calling is in another call and I am waiting. I usually don't like to disturb people when they are in another call so I promptly hang up. But I've noticed that my **HTC Desire S** does not tell me that information. Is it by design ? Is there anyway I can enable this feature? An app perhaps? Or are all the phones running Android have this feature turned off ? Just to clarify, I am **NOT** looking for activating call waiting on my phone so I get an alert when another person is calling me. I want to know when a call *I* initiated is in call-waiting on the other end.