I hadn't thought of that, and I was wondering where you were going with this. What frequency does Bluetooth operate on? (mobileinfo says 2400-2483.5Mhz in US) I don't think this is a interference hack.
I've used both Skype and Gizmo on my N810W without fail, but never with a HSP. If some party prevented Bluetooth audio services to prevent VoIP, it was a poor implementation.