If you’re totally new to mobile phones, or even if you’re well-versed in mobile devices, this is a superb article from late December 2012 on carrier differences in America, Europe, and elsewhere. It also mentions the MVNO subset of carriers which is, in my humble opinion, a boat not to be missed. Or, at the very least, a boat you should familiarize yourself with. You owe it to yourself if you hate being the proverbial “last person to know”. Here’s the link: