Most of the OTs are fertile. Some OTs gives seeds only if they are pollinated with pollen from 10-20 different hybrids. I have been told that a OT grown from seeds might be more fertile than it's parents, and give many more seeds than it's grandparents. Silk Road gives 20-30 seeds in each pod if pollinated with OT pollen. If it's pollinated with pollen from 4n trumpets the pods may have 30-50 seeds in each pod.
For 4 years I have been trying to get seeds from my OT lilies. The first years I had only a few older hybrids. Got no seeds. This year a friend of mine send me pollen from some OT seedlings that he knew was fertile. Thanks to that pollen I got many seeds from many of my OT lilies. But next year I will not pollinate any of the older OT lilies I have. They just gives me disappointments.
