This name is featured now and then on the BabyCenter.com naming polls, and people regularly find it "classic". I'm not at all sure what they mean by that, but I've never seen or heard of a Paige in South Africa, and we're usually up with the trends (Megans, Taylors, Kims and Savannahs abound).
My guess would be that it started as a surname used as a given name, and therefore probably migrated from boys to girls, changing its spelling on the way. Is that right? And is there any documentation about when this happened - popularity charts don't help much until a name becomes popular enough to show up.