If infants who are less than 2 years old travel on THAI Smile and are with an adult. The child's age must be at minimum 7 days old, and must not exceed 2 years of age. You can purchase tickets for infants through the THAI Smile website by selecting an infant passenger, or by calling to the THAI Smile customer service at 1181, 02-118-8888, or at the THAI Smile Service Center located at the airport.