My Ideal Cellphone

The cell phone has improved its functions for 10 years; however, i just need one more convenient function. I think most kinds of cell phone cannot work outside area. I f it works, its cost is too high. Therefore, at first, we need a mobile that can work around the world. Many international students will be satisfied with it. I believe that most people think they do not need functions any more. This is because there are lots of functions in it. We have phone, text message,Internet, music player, camera and more in it. If it has more options, nobody can use all the functions. So, what I want is only a worldwide network.