Task: Question Answering
Input (English): I was walking down the street with my phone in my pocket, when it began to vibrate.  I pulled my phone out of the pocket and looked at the screen.  The screen indicated that I was receiving an incoming phone call from my sister.  I pressed the button on the screen marked "accept" to indicate that I wanted to accept the call.  I then lifted the phone to my ear and said "Hello, Sister!" in a pleasant voice.  My sister was calling to discuss the details of our upcoming family vacation this summer.  I confirmed that I agreed with her hotel selections for our vacation.  We chatted for a while, and then she indicated that she had go to an appointment downtown.  I told her that I was glad to have had a chance to have spoken with her, and that I would speak to her again soon.  I pressed the button to end the call and hung up the phone. 
Question: Who answered the phone?
Output (English): The person telling the story