answer: Nathaniel Brown calls to speak with Miss Collins, but she's out. Thus, #Person1# notes down his number and will have Collins call him back.
documents: #Person1#: Hello, this is the International Student Office. This is Leah. How may I help you?
  #Person2#: This is Nathaniel Brown, from English Department. I'd like to speak to Miss Collins about my accommodation situation.
  #Person1#: Well, I'm sorry. She is out for lunch at the moment. Can I take a message?
  #Person2#: Sure. Can you have her call me back on my cell phone number?
  #Person1#: OK. What's your number?
  #Person2#: It's 07787367688.
  #Person1#: Let me repeat that to you. That's 077873676688, right?
  #Person2#: No, there's no double 6. It's just 07787367688.
  #Person1#: I got it. When should I have her call you back?
  #Person2#: Anytime before 6:00 PM tonight.
  #Person1#: OK, Nathaniel. I'll have Miss Collins call you back sometime tonight before 6:00 PM.