Looking for the cheap flight tickets, dial the toll free number 1-844-640-1484 of Sun Country Airlines and get exclusive deals and offers on the booking of flight tickets. Online Check-In: Online check-in is available 24 hours - 1 hour before the scheduled departure time for travel within the U.S. 50. If traveling to Mexico, Costa Rica, or the Caribbean, check-in at the airport with a Sun Country agent. Travelers must also check-in at the airport with a Sun Country agent if assigned an exit row seat; traveling with infants or groups larger than nine people; or if an unaccompanied minor is traveling. Sun Country Airlines, or Sun Airlines, is an American airline which is headquartered in Minneapolis, United States, and flies to over 45 destinations within the United States, Mexico and the Caribbean. The airline was founded in June 1982 and first began operations in 1983. Sun Country Airlines flies from Minneapolis to destinations that includePunta Cana, Montego Bay, Liberia, St.