I know they are a tough one to get rid of because of their hard outer shell that prevents chemicals from getting to their body. I hear a lot that alchohol and a q-tip work well, but may be time consuming if it's a large infestation.
I know there's a lot of posts about scale on the board. If you do a search I'm sure you could find a lot of helpful info that way!
You can start with the soap and water thing or Qtips and alcohol. but when I have this kind of insect pest, I want these critters DEAD! So I use the Bayer products.... Bayer Advanced 3-in-1 or the Rose Insectcide. They can be sprayed on the plant and used as a soil drench so it will be taken up by the plant as a systemic. If they are on catts, make sure you get down into the axial.
Bayer 3 in 1 systemic or GardenSafe work great. So does neem oil but I'd be very, very careful using neem on Phals, on everything else though, it works great.
There have been quite a few posts lately about this and just recently read (I think, by Sue) that alchol and 409 (50/50)...spray the entire plant, let sit for a minute or 2, rinse and repot into fresh medium.
The other thing about scale to keep in mind is that whatever you use must address the issue that the adult is the waxy larger mass and must be killed as well as the small tender juvenile insects. If you don't use something that gets both, you'll never be free of scale!