Error 0x80EE000F

Value: -2131886065 | 0x80EE000F | 2163081231

What does it mean ?

RTC_E_SIP_AUTH_HEADER_SENT  
Authorization header was sent in a previous request
Value: 15 | 0x000F | 0b0000000000001111

Where does it come from ?

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

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