Mary calls John, asking him to give a message to her parents. 
W: Hello, Uncle John, this is Mary. 
M: Mary, what a surprise! How are you doing in China?
W: Not bad. Could you do me a favor? I've been trying to call my Mom and Dad for almost an hour, but the line is always busy. Nobody else could have been talking with them on the phone for so long. They must have hung up the phone improperly. Could you possibly go there in order to let them know that?
M: OK. No problem.
W: Thanks a lot, Uncle John,
M: You're welcome.