All of us cut [or have to cut] incoming phone calls sometimes. But some people cut calls too frequently. And it feels very rude. Are you guys so busy? All the time? Not really. No one is. Then what are you trying to show [if anything] by giving the busy tone so often? I myself, as far as possible, pick all/most incoming calls and tell the caller that I'll give a call back as soon as possible. Picking call - even if only to say that I'll call back - is a much more warm and respectful action from the perspective of the person who calls us.