I originally bought the Voyager 510S which is a base unit to turn my desk phone into Bluetooth. The headset works with both the desk phone and cell phone. When I am at the office, I am wireless to both and the set responds to whichever one rings. When I am out, I am wireless to the cell. For me this is perfect. Making it even better is the service I have received from Plantronics over the years.I lost the headset so bought a replacement from Amazon - also good service. The headset works well and is clear, but the choice is even more simple for me as I need the duplex function that allows it to work with more than one device at a time. I might have gone for a smaller or more fashion conscious one if I didn't need this function.Bottom Line - I am very pleased.