Where was the phone when you discovered it this way? Have you installed anything on the phone recently?

My phone is a Samsung Galaxy SIII with ATT.

As I was sitting watching TV I heard someone saying Hello? Hello? Hello? several times. Finally I got up thinking it was on the computer but it turned out to be the phone which was lit up and in the speaker phone mode. And the voice which had a heavy accent maybe India was a live person still saying hello. So I said hello and they responded asking for some name. I said 'I can't understand what you are saying'. And they said 'Oh okay' and disconnected.

I had not made any calls that day so how without me answering it did a connection open with a caller and in speaker phone mode?

Does anybody have any theories? Does this happen to other people often?