As opposed to reading them? AFAIK there's nothing out there that really works. I have verizon and there were a few things I did with my daughters phone: 1) paid for the Parental Controls (I think it's called something different now) which allowed me to set time limits (bedtime, school time) for the phone to work except to call her parents. This also allowed me to turn off her cellphone as punishment if needed. 2) This feature also let me see who was calling/texting and sending MMS and if needed I could block those numbers. I did have to do that to a certain older boy that harassed her to no end. 3) Since I pay the bill, I would regularly and randomly ask for the phone to be handed to me unlocked and I would read the messages. After doing that a few times seeing the kind of CRAP that she would get during her middle school years she would open up and alert me when she was getting bad stuff --- on her own!
I learned a LOT by doing this. Let me just say this: if you're the parent of a boy around Middle School age he's probably the problem. I am NOT kidding! My daughter got requests for "nudz" and "show me your boobs" daily, often several times a day. Thankfully she survived this and looks back on it with some humor. She tells me that if she ever has kids and has a boy, he'll be taught to treat women better! LOL
My advice. Take what you pay for and read stuff off the phone/computer/device and set limits on usage until they're old enough to be responsible. Spying on your kids/wife/husband etc gets very messy.
