Did you see my post on how to check it?
http://atrl.net/?p=36447037

Definitely not Sprint. That was the worst customer service I have ever experienced. I switched back to T-mobile.

you should be able to... I mean I guess I haven't had an iPhone in awhile but

Depends, but T-Mobile is great for something cheap and if you are always in a major city, or travel to europe as you can use the Telekom lines

Verizon is great if you're traveling within the USA, because their coverage is good, but their rates are too high

AT&T is a better alternative to Verizon, as they don't do overages

Sprint is awful tho

AT&T and Verizon. But switch to AT&T.
If you want the cheap services, you won't have peace of mind.
I switched to Sprint because they offered me double the data for less money than I pay AT&T. The service was so bad, I had to cancel after 2 days and had to pay to cancellation fee Sprint was going to pay AT&T (even tho I was going back to at&t and keeping my number.) Lost $300 and my old phone that Sprint refused to give me back. So I had to pay for a new phone again. Another $200
Moral of the story: get a 2 years contract with either AT&T or Verizon and stick with them. When the contract is over, just continue on a month to month basis. Switching to save money isn't worth the bad service and at the end of the day, they are all crooks

AT&T

I waste so many data and I don't know on what

I have Ting. They're a MNVO that uses Sprint as the main carrier with free roaming on Verizon. I've used it a year now and I've had zero service problems. They're also rated the highest in customer satisfaction. What's nice about them is that your bill could be as low as 6 dollars a month. My average bill is 15 bucks. You pay for what you use.

You can go to Ting.com and use their rate calculator and compare your current usage and bill and see if you would save by switching.

Data is probably the easiest to run up but with a little oversight you can make sure your data doesn't go over 500mb. I stick to wifi and refrain from using apps unless I need to. Best option for somebody who needs a smartphone but doesn't want to pay a high bill. Unless you're lucky enough to have unlimited data on a cheap plan, it should save you money. But that's why they have a calculator so it's easy enough to find out