How do I get through to Allegiant client assistance? Full data about Trip Flex is accessible here. Clients can drop reservations online through the Manage Travel segment of www.allegiantair.com and can drop or make changes to reservations by reaching Allegiant's Reservations Center and talk to a person at allegiant air on this number (702) 505-8888 toll-free. https://onlineairlinesbooking.com/how-do-i-talk-to-a-person-at-allegiant-air/