what do you when you call someone on the phone by mistake?

I think it would be rude just to hang up. Beside they can tell who called them. I would tell them that I called them by mistake. If I knew them I would ask how they have been and then tell them I will talk to them later and apologize for the mistake. If I don't personally know them then would let them know I called wrong number and "sorry to disturb you" . One time I accidentally called a friend of mine and was not aware that I had even done so. Somehow I hit a button on my phone and they could hear me but my phone was in my purse or pocket. It was kinda weird.

I would apologise first to the person and tell him that it was a mistake. Hanging up the phone usually results in the person calling back (if call id is available) and enquiring on the missed call. There you land up doing the same thing again.

I apologize and say that I got a wrong number.

The first thing I do is ask if it is the phone number and I will tell them the number that I have dialed. If they say that it is the wrong number than I apologize and say that I have gotten the wrong number. For me that is simple curtsey.

Hello, Suppose by mistake the phone call connected to an unknown person I will first ascertain if it is the number i am wanting and if it is not that i just say SORRY, WRONG NUMBER and disconnect the link.thanx.

I'll talk to the person and will have to say sorry...I'll just be honest that I accidentally press the wrong number and hang up... ;p