这是中国式的回答,英语中不说who is that speaking
一般可以有以下的回答方式
May I know who is calling please?
这样比较客气
一楼的回答用can也只能是说语法正确,我在美国从没听过有人这样接电话问对方的,或许中国老师教的学生会这样用吧
或者直接问
Who's calling please?
May I tell him/her who is calling please?
这些都可以
Can I ask who is calling ?
who is that?
who' s that,,回答要用this is……speaking.