So today I bought a Plantronics Discovery 975 Bluetooth headset, from a local AT&T store, to use with my HTC Tilt 2 and a cheap Motorola phone that I use for work. I had absolutely no problem pairing the headset with my cheap Motorola, but it refused to pair with my Tilt 2. After multiple failed attempts, I finally called HTC. to see if they had any suggestions. The wonderful representative at HTC did some research and told me that there are apparently three different “stacks” for bluetooth devices, and if the headset operates on one stack and the phone operates on another stack, they will likely not be compatible. Hmmmm, that would explain my problem, but does anyone know if this is true? I am very upset that this wonderful, high end headset won’t work with my high end phone. Thanks.