I'm looking for Manager Wang.
This is he/she.
You've called the wrong number.
What number are you calling?
She is not in. May I know who's calling?
May I ask when will he return?
She'll be back around 3 in the afternoon.
Then, I'll call back again at 3PM.
He's not in. Would you like to leave a message?
Please ask him to call me upon his return.
他回來，我叫他 給你 （打/回）電話。
I'll instruct him to call you upon his return.
I introduce U.S. products to you.
When he returns, I'll tell him.