Error 0x00EF0064

Value: 15663204 | 0x00EF0064 | 15663204

What does it mean ?

RTC_E_STATUS_INFO_TRYING  
Trying
Value: 100 | 0x0064 | 0b0000000001100100

Where does it come from ?

FACILITY_SIP_STATUS_CODE  
SIP - Session Initiation Protocol (VoIP)
Value: 239 | 0x0EF | 0b11101111

Other Errors for FACILITY_SIP_STATUS_CODE