Error 0x80EE005E

Value: -2131885986 | 0x80EE005E | 2163081310

What does it mean ?

RTC_E_SIP_ADDITIONAL_PARTY_IN_TWO_PARTY_SESSION  
Adding additional parties to two party session failed
Value: 94 | 0x005E | 0b0000000001011110

Where does it come from ?

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

Other Errors for FACILITY_RTC_INTERFACE