Any national/regional differences or is it all personal preference?

There was a pizza place in my hometown with the number 444-4333. They always gave it as "four 4's, three 3's."

There's a comedian (Kevin James) who does a great routine about the frustration of dealing with people who don't follow the standard bah-bah-bah...bah-bah..bah-bah rhythm when telling you their number (Yeah, my number is one...twenty-one, two-oh-three, six...teen). It makes it almost impossible to remember.