dǎ diànhuà shí xiān shuō nǐhǎo wǒ shì néng ràng duìfāng mǎshàng zhīdào nǐ shì shéi

打电话时，先说“你好，我是……”能让对方马上知道你是谁。

When making a phone call, starting with 'Hello, this is...' lets the other person know who you are right away