It's every parent's dream — or nightmare — when teenagers get their driver's license:

Where are they going and how fast are they driving? Now, you can ease the anxiety by signing up with a service that combines global positioning satellite systems with cellular phones to track your child's whereabouts.

Teen Arrive Alive allows you to monitor a newly licensed driver using a Nextel phone that is equipped with GPS. As long as the phone is on but not being used, it will transmit signals that you can access online to check the car's location and speed.

If your child is on the phone, you'll see the last location before the conversation started. And if you think your teen might become very talkative to prevent you from monitoring speed, you can slap an "Am I Driving Safely?" decal on the car. It encourages observers to use a toll-free number to report unsafe driving to a service that will relay the message to you via e-mail or telephone.

Donna Butler of Wimauma, Fla., is a believer. She uses Teen Arrive Alive to keep an eye on her 17-year-old daughter, Danielle. Butler views the service primarily as a deterrent to keep her daughter from speeding, but she cites another advantage. When Danielle got lost one night and called home for help, her mom went online to see where she was and gave her directions.

"It is an awesome program," Butler says. "It gets youngsters out of worrying about peer pressure. Danielle can say, 'I can't drive any faster' and blame it on Mom."

The program even works when Danielle is in a friend's car — as it did one time when Butler saw that the friend was cruising at 85 mph.

Teen Arrive Alive (www.teenarrivealive.com) costs $15 a month — add $5 if you want the decal program — after a $50 activation fee. The GPS-enabled phone is free, but you must sign up with Nextel for phone service.

ULocate offers a similar service. The program also requires Nextel service and one of five Motorola GPS phones. Subscribers can watch a driver's progress and receive online reports of the car's speed, direction and location every two minutes. ULocate (www.ulocate.com) is $11 a month for one phone and $8 for each additional phone, plus a $10-a-month data plan on top of the regular Nextel plan. Phones range from $80 to $150, although discounts are often available.