This is my second Plantronics 510. I bought it for my wife who uses it with her Razr. She is on the phone non stop while she works and the first one lasted for about 2 years with no problems and then I think the battery finally gave out. Anyway this sounds very clear, with good volume, and no complaints from the people she calls. We tried some Motorola headsets but they can't touch this one for call quality. It is a little big for my taste, I have a smaller Plantronics unit that sits in the ear, but this won't fall out because it hooks around the ear. It is a great value and highly recommended.