Plantronics C520, C510 Troubleshooting, Headset, I cannot hear caller, Callers cannot hear me

Contents Blackwire C510/C520 USB Corded HeadsetUser Guide Contents WelcomeWhats in the package BasicsWelcome System RequirementsComputer DisplayWhats in the package Carrying caseBlackwire C510 Headset with inline controller Blackwire C520 Headset with inlineSmart Sensor Feature BasicsHeadset inline control icons FunctionWearing Your Headset PC Audio Setup for Windows 7 and Windows PC Audio Setup for Windows XPDaily Use Incoming/Outgoing Calls 1 To place a callAdjust Your Headset Volume Listening VolumePlantronics Spokes Software General use Plantronics Update Manager Check for Updates AutomaticallyCheck for Updates Manually Install UpdatesTroubleshooting HeadsetI cannot hear caller Callers cannot hear meSmart Sensors My headset stops responding tobutton presses The Auto Answer call function isNEED MORE HELP? Plantronics, IncPlantronics BV 345 Encinal Street