customer cannot hear me although I can hear him.

@jhallak01 ,Jack, If you have installed/setup as per your manual you may want to try the recommended reset procedure below and if still no go return for replacement/refund.

Press in and hold the mute control (A) and the talk button (B) until the talk indicator light (C) on the headset starts blinking rapidly. Release both buttons.

Press and hold the talk button (B) again. Wait for the talk indicator light to stop blinking, then release the button.

Disconnect the CS50-USB/CS60-USB from your computer's USB port.

If you are also using an AC power supply, disconnect it from the bottom of the base.

Wait 5 seconds, then reconnect the AC power supply and USB cable. The system reset is complete.

Test the headset to ensure it works properly.

Find below a link to CS50 Knowledge base/trouble shooting/manual. Good luck. I hope this helped you out, if so let me know by pressing the helpful button.

http://www.plantronics.com/us/support/pr...