Parents are often worried their teen driver is using a cellphone behind the wheel, but a new study shows they're usually talking to their parents.

Researchers at the American Psychological Association found about 53 percent of teens who talked on the phone while driving talked to a parent, while 46 percent talked to a friend.

But when it comes to texting, messages were more likely to go friends than parents.

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Teens who participated in the study said they're expected to answer the phone when their parent calls.

In some cases, the parent might continue to call until the teen picks up.

Texting and driving is against the law in North and South Carolina. The only state in the nation without a ban is now Montana.

North Carolina troopers have found it difficult to enforce the law because it's hard to prove a driver was texting.