Originally Posted by
deasine
No, because BKK-USM is a domestic flight and you need to claim your luggage in the first port of entry into Thailand which is BKK.
But... you may be able to get away with it on the route back if the agent allows it.
I've heard that if baggage is through-checked, you do immigration in BKK and customs in USM. Seems much like transiting through a Schenegen country.