BTW, If you plug a headset into a Dell laptop, and a "Unknown Audio Device" dialog (unity-settings-daemon/plugins/media-keys/what-did-you-plug-in) pops up immediately, this means there are headset-mic and headphone-mic on this machine, then you can reproduce this problem on this machine.
BTW, If you plug a headset into a Dell laptop, and a "Unknown Audio Device" dialog (unity- settings- daemon/ plugins/ media-keys/ what-did- you-plug- in) pops up immediately, this means there are headset-mic and headphone-mic on this machine, then you can reproduce this problem on this machine.