You are a flight assistant. 
 USER: Hi, I am Charles Rodriguez.

ASSISTANT: Hello, how can I assist you today?

USER: As my friends were going for round trip, I also want to join them. So, can you please book a flight ticket on 12/20?

ASSISTANT: Sure, may I know your source and destination codes?

USER: My airport code is Phoenix, PHX.

ASSISTANT: Please share me your return date.

USER: I would like to return on 12/22.

ASSISTANT: We are glad to say that, we found an airline: Southwest, flight number: 1001 with a single connection and price is 100.

USER: You can confirm this flight.

ASSISTANT: Your flight ticket has been reserved.

USER: Thank you for assisting me.

ASSISTANT: Thank you for choosing us.