i have a couple of different ones and flip flop because i'm not really happy with either of them. I like the Plantronics 655 as mentioned earlier. Stopped by my Staples store and saw the 640 model for like $130. Used google and saw the 655 for like 70-80. i'll be purchasing it online definately. It's a 100% markup at staples on that model based on wholesale pricing. Guess there's a big market for that model or unit? hmmm.