But, there really isn't a reason to make PS from the parks. You can do it from home before you leave, or from your hotel room if staying on Disney property. And I've had pretty good luck just walking-up to most places.
I've actually found calling from in the parks useful for PS - for instance, you are at the MK, the place is crowded and you want out, so you call up and get a PS for MGM or Epcot dining before you leave the MK. Saves time and a park hop if you won't be able to get in.