Are there any Iphone 3 apps that hides all your calls and texts?

My parents are paying for my phone while they help me through college. They monitor my phone bill to see if I'm talking to my boyfriend. My boyfriend and I have a child together and we're trying to work things out so we can be together for the sake of our child. I wouldn't normally have my parents help me with a bill but since they are paying my way through college it was my only option for me so I can continue with my education.
My question is, Are there any iphone 3 apps that won't show any phone calls or text on the bill?

Added (1). It application needs to be free.

No there's no app like this for any kind of phones.

No there's no such apps.