FYI, IATA numbers are basically the TA's ID number & you do need to have the right ID card and would be very suprised if you weren't ID'd. Also, when you put the IATA number in, it's not for the discount...it's so the companies know which travel agent to pay the commission too. To get the travel agency rate, you generally need to get the right rate codes (at least with rental cars & hotels - not sure how airlines interact with the GDS systems).