When calling someone on the telephone or otherwise seeing if someone is present, you can use the Mandarin Chinese expression zài bú zài, which literally means “here not here.” This is the positive / negative way of forming Mandarin questions, so another way to say this is with the interrogative 嗎 (ma) particle.

The Chinese character 在 zài means “located at,” and the character 不 bù is a negating particle used to form negative sentences. When used before zài, the fourth tone of bù changes to a second (rising) tone.

Zài bú zài is a question meaning “Is he / she / there?”
Examples of Zài Bú Zài
 
    Qǐng wèn, Wáng xiānsheng zài bú zài?
    請問, 王先生在不在?
    请问, 王先生在不在?
    Excuse me, is Mr. Wang here?

    Or the “ma” question particle can be used:

    Qǐng wèn, Wáng xiānsheng zài ma?
    請問, 王先生在嗎?
    请问, 王先生在吗?
    Excuse me, is Mr. Wang here?