l am doing some reporting on Lync - from the Call Details database (LCSCDR).
I am calculating the call duration using the SessionIdtime as the call start time and the SessionEndTime as the call end time.
I have noticed that on some occasions this gives a negative result (ok not very often)
"SELECT DATEDIFF(ss,sd.SessionIdTime,ISNULL(sd.SessionEndTime,sd.SessionIdTime))
FROM SessionDetails AS sd".
My questions are
a) why is the sessionendtime sometime null ?
b) why is the sessionendtime sometimes less than the sessionidtime
c) what is the responsetime ?