answer: #Person1# thinks #Person2# bought the other handset, but #Person2# changed the case because #Person2# bought all cases.
documents: #Person1#: Have you bought another handset 
  #Person2#: No, it is the original one. 
  #Person1#: This is silver gray,while I remember your handset was black. 
  #Person2#: I have changed a case for it. 
  #Person1#: Can a handset case be changed? 
  #Person2#: Of course. That's why I bought this type. I can change its case frequently, so it is novel to use it. 
  #Person1#: How many cases are accessible? 
  #Person2#: There are two more, one is orange and the other is pink. I have bought them all. 
  #Person1#: It's really going to be fresh all the time.