True. The page table stores one of two things for each virtual page number: (1) it can store a physical page number, if the virtual page is present in memory; or (2) it can store an indication that the page is not currently in physical memory. If the processor finds case (2), it does a trap to let the operating system decide what to do.

That is the link between the very fast but inflexible memory management unit of the processor and the slow but flexible software of the operating system.