Who is that?或Who is there speaking?英语打电话时说“我是……”要用“This is……，问对方是谁用“Who is that? “ ，不能用“I'm……” 和“ Who are you? ”
标准的是 who is that （on the phone）？ 回答 this is ..加名字
WHO ARE YOU?
what‘s that？
who is that ?
