One day my boss and I happened to passed by a Thai restaurant name "PHUKET", he asked me how it is read and I read the PH as PH, then he told me why they have to spell it that way when they can actually spell it with P without the H. I simply said maybe that's how it is. That conversation never leave off my mind, for sure there is really answer to that but I really don't know why it is spelled that way.