Physics engines use their own collision meshes and methods, which is why you have to register physics objects first - as a result physics objects ignore regular OBB entities. You can even visualize what's happen inside and with physX and their collision meshes when you register as an nvidia developer and download some SDKs.
"Falls das Resultat nicht einfach nur dermassen gut aussieht, sollten Sie nochmal von vorn anfangen..." - Manual
Thanks Superku, I've seen physics ents pass through obb, and obb jump on physics ents.
Just for curiosity sake, as this is clearly old info I'm remembering, did A5-A7 physics have a rule warning to "never make a collision" between move(not c_move) and physics ents? This would have been either Bullet phys engine or ODE phys engine.