Is that you,John?
(一) 打电话人找你  Is Daisy there? (Daisy 在吗?)Speaking. 我就是。/This is she. 我就是。This is Daisy. 我就是 Daisy。That's me. 我就是。
情况 (二) 打电话人要找人不在
May I speak to Mr. Gates? (请问 Gates 先生在吗?) He's not here right now.他现在不在这里。He's out. 他出去了。You've just missed him. 你刚好错过他了。He's just stepped out. 他刚好出去了。