SAN DIEGO -- A new service being offered by Sprint called the "family locator" is now allowing parents to track their children.

If a child's cell phone is on, parents can track him or her from a handset or computer, using the built-in Global Positioning System function on the phone. An interactive map pinpoints the child's real-time location, including an address and nearby landmarks.

Some Sprint customers who are parents said the service is tempting.

"I think it is a great idea. With everything happening these days, you need to keep track of your kids all the time, makes you sleep better at night, " said Sprint customer Martina Andrew.

It's nice for parents, but according to some, it's not so nice for teens.

"I don't want my parents to always know where I am at, " said one concerned teen.

Privacy experts also worry about a slippery slope when it comes to monitoring and the long-term effects on children.

"(If) it's now going to be OK for children to be GPS-tracked, when is it going to be OK society wide?" said Beth Givens, of the Privacy Rights Clearinghouse.

"They're going to grow up with (a) picture of somebody watching them. Are they going to grow up less of a risk-taker? Not speak freely?" said Givens.

This is an opinion some call alarmist; they said adding a little less freedom is a small price for more safety.

Sprint points out it's not just one way surveillance.

Children must agree to the terms of service, and they also receive an alert whenever their parent has searched for them.