That's Dendrobium farmeri, a close relative of Den. thyrsiflorum. They differ in that Den. thyrsiflorum comes from montane regions, has taller canes with more flowers per spike, which are small and white with a lip that's completely orange. Den. farmeri is a smaller plant from lowland regions with fewer flowers per spike, but which are slightly larger, with a pink flush (although I think there's an "alba" variety with white flowers) and a lip that only has an orange throat instead of being orange in its entirety. Den. amabile is another closely related species that has flowers that are similar to those of Den. farmeri, though they are larger, more "shapely" (rounded and fuller) and the plant itself is similar in stature to Den. thyrsiflorum and, like this species, comes from montane regions (both these species need a colder and more prolonged rest than Den. farmeri to bloom well).