+1-844-414-9223 If you want to upgrade your flight seat on Southwest and you didn't find any relevant solutions, then just visit Air1Network. They have a blog called "How to Upgrade Economy to Business Class on Southwest," through which you can upgrade your flight seat easily and quickly. For more information, call Southwest's customer service line at 1-844-414-9223, which is open 24 hours a day, seven days a week.