Error 0x80EE005D

Value: -2131885987 | 0x80EE005D | 2163081309

What does it mean ?

RTC_E_SIP_CALL_CONNECTION_NOT_ESTABLISHED  
Call connection has not been established
Value: 93 | 0x005D | 0b0000000001011101

Where does it come from ?

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

Other Errors for FACILITY_RTC_INTERFACE