If I remember correctly, you have to remove your sim card from your phone along with not having a phone number (unless it's a Japanese #). LINE is stupid. They don't like gaijin money evidently. Lots of people would be more than willing to pay whatever they asked to get access to the Japanese-only stuff but I guess xenophobia runs rampant...
(Don't blame it on "licensing" either, b/c that's just another form of xenophobia ー if you really want to do something, you'll make it happen, LINE. You just don't wanna do it.)