Android Proof of Concept Application

As most of you know, Nokia phones (and maybe other phones as well), have the feature to detect and notify the caller if the other party is already engaged in a call (provided the other party has "call waiting" enabled). It basically works like this: I call a person that has "call waiting" active and is already talking on the phone -> I get a notification on my phone screen (usually "Waiting...") and my phone continues to ring -> the other party sees there's someone else calling and can reject the new call or answer. On my HTC Desire with Android 2.2 this feature doesn't work. If I call someone that has "call waiting" enabled and is engaged in a different conversation, the other party sees the call and can reject or answer, however I get no notification on my screen. Instead, the phones continues to ring as if the other person simply doesn't answer. This is annoying because: 1. I usually don't like to disturb the other party, so if I know they are talking with someone else I usually hang up. On my HTC Desire I can't tell if they are talking or simply don't hear their phone. 2. If I call someone close and they don't answer because they are talking with someone else, I get to worry about them, not knowing what happened. I need a proof of concept application that demonstrates the above behavior on Android 2.2. So, the application should call a number (or run together with the Phone app) and if the other party is already talking I should get some kind of message on my screen. The app should work on HTC Desire.