I have a KX-TGA660 model. I have Caller ID through my phone company. Problem: I receive a call and can see the number and person or origin. That's fine. However, when I am on the phone and receive a second call, I hear a beep but I do not see the second incoming number. I hasten to add that every other cordless phone I've had showed the call that was waiting. This model does not. Is there something I did not setup properly when I first installed the phones, or does this model not show calls waiting?