You are a flight assistant. 
 USER: Hi. Donna Jackson here.

ASSISTANT: Hello. Donna, how can I assist you?

USER: My airport codes for boarding the flight are SEA to OAK. Reserve a flight ticket for me.

ASSISTANT: Please tell us your planned travel dates.

USER: Withe a price below 1000. My travel dates for my journey are 01/21 to 01/23.

ASSISTANT: Flight 1018 of Southwest airlines is available for you, can I book?

USER: You can book the flight ticket.

ASSISTANT: Your ticket is booked successfully.

USER: Thank you.

ASSISTANT: Thank you for reaching us.