answer: Mr. Roberts asks Sara to call Mr. Jacob and tells her the extension number.
documents: #Person1#: Could you call Mr. Jacob for me, Sara? I need to go over some stuff with him.
  #Person2#: Of course, Mr. Roberts. But, could you tell me his extension number again? I haven't got all the numbers down yet.
  #Person1#: Sure, it's 4-8- 7-2. Don't worry. You're doing a fine job.
  #Person2#: Thank you very much. Mr. Roberts.