How to purchase an Iphone that will work on all service providers?

I have been recently interested in looking at purchasing an Iphone and getting a better plan. I'm a little confused on if there's a way to purchase an Iphone that will work for all plans. I'm primarily looking at prepaid plans as they are cheaper. What would you suggest? Plus I haven't really been using my phone very much and don't really know how many minutes I would use. I would like to have internet and texting for sure but a limited amount of minutes for calling is fine.

There's no phone that will work on all carriers but there are phones that will work on most. This is an Unlocked phone. You can buy these online pretty easily also if you buy straight from apple that would be unlocked too. But you have to buy the full price one. And you can't use these phones with some big companies too, these companies include Verizon and Sprint. Neither of these companies will allow you to use your own phone unless it is also from their own company. I have heard T-Mobile is good but i looked at their plans online and if you want a pre paid plan they require you to get unlimited texting and calling which i don't need nor want. I don't know if i was looking at it wrong or maybe that online only and i could do something different if i go to the store. But it was something that you probably don't want.