My Bluetooth headset (Motorola HS810) doesn't seem to notify me of incoming calls when I'm already on a call (either that, or I'm going deaf). I thought it might be the headset, but I've noticed the same thing when not using it. For example, I'll be on a call and looking at my screen the entire timme and when I finish, I'll see a Missed Call notification. Is this a Treo defect or a problem with the headset, or both?

m100->Tungsten W->Treo 650