[HKEY_CURRENT_USER\ControlPanel\Volume] Volume"=dword:0xFFFFFFFF; 0 is the min Vol. 0xFFFFFFFF is the max Vol. You can explore the reg given below for changing the volume in Handset/Headphone/VOIP mode [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\WaveDev\WAN\Headset] [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\WaveDev\WAN\Speakerphone] [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\WaveDev\WAN\Headphone] [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\WaveDev\VOIP\Speakerphone] [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\WaveDev\VOIP\Headphone] [HKEY_LOCAL_MACHINE\Drivers\BuiltIn\WaveDev\VOIP\Handset]