Why is iphone 4s using data every hour

Due to the cost, I only have 300mb of monthly data. I was checking my data usage and discovered that every hour, the phone is using 1-3KB of data. Why? I do not stream anything, download anything, surf the web. I talk and text--nothing more. Don't even text daily nor talk daily on the phone.

I have two apps--Solitaire and flashlight on the phone. All others came with the phone I was told to turn off cellular data--then voicemails didn't come through. Turned it back on.

No one can tell me why this data is being used. It's not that much being used, but it adds up. I do not have much as it is, and if I really need it, I would like for it to be there. Any ideas?