Because now there offering there new plan. Which isnt a 2 year contract anymore. So if I buy the phone outright for $550 I pay $70 dollars a month for unlimited everything. Which I also think is high. If I dont buy the phone but instead do there new "JUMP" plan I have to pay for my data plan which would be $70 a month plus another $20 on top of that for 24 months. 

They are both phone service standard.. The way you make a call.. Now europe asia and africa is gsm but most of the americas are cdma.. The us has both services.. I think At&t And tmobile are using the gsm standard and the other cdma.. 

This affects the phones you can buy.. Depending on the carrier you want to use you have to have either a cdma or gsm compatbile device.. Now CDMA Versions of phones aren't always made or not available to buy freely outside the carrier..