Previously I used a Motorola HS850 and found its sound quality to be a bit lacking, so after reading the positive reviews on the plantronics i was excited to pick one up.In all ways, the Plantronics 640 is great, with the one major exception that there's static when you use it.It appears that the static is related to poor RF performance. If I hold the phone and within 6 inches of the earpiece, all static goes away. However, if I hold the phone on the other side of my head, the static appears. Put the phone in my pocket and the static is sometimes so prevalent I can't carry on a conversation.I tried pairing the 640 with my Motorola e815, a friend's Samsung, and my bluetooth laptop. All were distinctly staticky.It's really too bad, because i do love the feel, the weight, the battery charger, the adaptors for other power adaptors, etc. It's otherwise very well designed! Your mileage may vary... I notice a treo user also reports static, but many other reviews don't.At this point, my plan is to wait for the Motorola H700 to come out and give that one a try. Hopefully it will have addressed my issues with the HS850.