IPhone 4S cellular data turns off on sprint?

The cellular data on my iPhone 4S (sprint) keeps turning itself off at random times when I'm away from the house. I can't figure out why. I set the data on, then a few minutes later, depending on where I'm, it's off. Even if I'm using data at the time. Any suggestions?

Go to sprint and ask for assistance they will probley replace you with a new one.