Once you have been assigned a Known Traveler Number (KTN), you must include this number in the ‘KTN' field of each reservation you make with a participating airline. The KTN also can be added when booking reservations online via a participating airline website, by phone with an airline reservation agent or with the travel management company making reservations. Save your KTN to any frequent flyer profiles, employer booking systems or online travel websites that you use.