Although the services are available 24*7, but for me the best time is to call them at night. I usually book flight ticket at the night time because I had a very good experience. But I always think that when is the best time to call southwest airlines. I have called them many a times whenever I booked flight tickets from southwest. And the best timing suits me at night. I have experience excellent response from southwest service team whenever I want to know my flight status or any other query.