Error 0x80EE0021

Value: -2131886047 | 0x80EE0021 | 2163081249

What does it mean ?

RTC_E_MEDIA_AUDIO_DEVICE_NOT_AVAILABLE  
Audio device is not available
Value: 33 | 0x0021 | 0b0000000000100001

Where does it come from ?

FACILITY_RTC_INTERFACE  
RTC - Real-time Communications
Value: 238 | 0x0EE | 0b11101110

Other Errors for FACILITY_RTC_INTERFACE