When you refer to 'IAP code' I'm assuming you mean Atmel's bootloader?

Also, why 0xF803? Atmel's example code jumps to 0xF800
I do, fortunately, know nothing about Atmel, but Philips changed their bootloaders from f800 to f803 to insert a LJMP 0 at f800 to prevent runaway code from entering the bootloader (maybe with the regs set for erase or some other disatrous operation). This cange has required change of many bootloader programs.

Erik