Blaatz,
I believe that Dwayneg gave you some good scenarios on how to figure this out for yourself, but think of this as how calls are made and received.
How many calls from outside the system did my extension have coming in to it. CALLS IN. This means a call rang directly to me or was transferred to me.
How many calls from outside the system ended at my extension that released the phone line for service. CALLs IN END. This means I did not transfer it to another person.
How many calls did I make outside the system. CALLS OUT. This is pretty self-explanatory.
How many calls did I make outside the system that ended at my extension that released the phone for service. CALLS OUT END. This means that I did not transfer the call to another person.
Hopefully, that clears it up for you a little better.
Thanks,
TE