Error 0x80EE005F

Value: -2131885985 | 0x80EE005F | 2163081311

What does it mean ?

RTC_E_SIP_PARTY_ALREADY_IN_SESSION  
Party already exists in session
Value: 95 | 0x005F | 0b0000000001011111

Where does it come from ?

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

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