I'm curious about how random calls wind up on a hotel bill.

When I checked out of my hotel this morning there were 6 outgoing calls on my bill - all to local numbers, and short, and all within a brief period of time at like 11:30 pm, when I was fast asleep.

So, dismissing "sleep calls" which I have no history of, and I can't imagine calling actual local numbers which would be in my memory, I can only figure that someone somehow charged calls to my room?

I got the calls removed, but, how do they wind up on a bill in the first place??