I'm embarrassed to say that I've never dialed out of the country or back in (at least, not that I know of!). Please excuse the ignorance. My grandfather was born on London in 1889, way before the telephone! LOL
I highly recommend the priority seating. I remember walking out of Tower of Terror at MGM, and my friend and I got this sudden urge to eat dinner at The Brown Derby. I called from the cell, and by the time it took us to walk there, we only had a 15 minute wait, as opposed to an hour for walk-ins. We enjoyed a very good dinner and finished just in time to make it to Fantasmic (Maybe I shouldn't have told anyone about my great experience - shhh!) It was like having a Fastpass for dinner! Of course, this luck doesn't work with Cindy's Table and the more popular character dining venues, but it certainly did help in this case.