Seattle ? With the help of technology, kids will no longer be able to claim they are at a friend’s house or at school when they really aren’t.

On Thursday, Sprint Nextel rolled out a cell phone service that allows parents to pinpoint where their children are by tracking their cell phone. The parents can flip open their phone or log onto the Internet and find their child’s location stamped on a map.

The technology, using global positioning system (GPS), has been available for some time, but it has mostly been geared toward businesses that want to track workers. Now the technology is available in easy-to-use consumer applications.

The child tracker is aimed at a burgeoning market – families with multiple phones on one service plan. Almost half, or 9.6 million, of Sprint’s wireless subscribers are part of a family plan, according to M:Metrics, a Seattle research firm. (Those numbers don’t include Nextel subscribers.)

In addition to the Sprint service, Disney Mobile last week unveiled its new wireless phone service targeting families at CTIA Wireless 2006, a wireless convention in Las Vegas. Among other things, Disney Mobile allows parents to monitor where their children are. The service is set to launch in June.

“They want a cell phone to be in the kid’s hands, but they want control,” said Parry Aftab, a lawyer with WiredSafety.org., who made a presentation alongside Disney at CTIA.

The Sprint service, using technology from Emeryville, Calif.-based WaveMarket, is called Family Locator. Once a family signs up, an application is loaded onto the parent phone.

The service, which can also be viewed online on a PC, has numerous protections, including passwords, so only people who have given permission can be tracked.

The password is used during registration by both the parent and the child. It can also be given to others, like a grandparent or baby-sitter.

The parent phone has four simple options: locate, messaging, manage or exit. After choosing locate, a map appears with the child’s location. The service uses GPS, but if it’s not available, it will locate the phone based on the nearest cell phone tower. The service will not work if the phone being tracked is off or is not receiving a signal.

Once the child’s location is found, a message goes automatically to the child’s phone.

The location can also be found from a Web site. Parents can manage other features at the site, including setting up a daily text message or e-mail that goes to the parent when the child arrives at school, day care or a specific address.

Family Locator is available on both the Sprint and Nextel networks. It can be used on about 17 phones for parents and 30 phones for children.

For $9.99, there are unlimited location requests for up to four phones. If both parents want the service on separate phones, they will have to pay for the application twice.

“There are times if your kid doesn’t show up at home when you expect them, and if you can see they are still at school or somewhere you know they are safe, that’s useful,” said Gerry Langeler, who has a 15- and 19-year-old son.

“You could call them, but they may have the ringer turned off, or they are in noisy place and they don’t hear it.”

For now, Sprint’s opportunity to target children and teens is fairly large.

Although it wouldn’t say how many subscribers are already equipped to use the service, M:Metrics estimates that Sprint and Nextel have 2.4 million subscribers ages 13 to 17.