Cell phones equipped with GPS tracking devices let you keep tabs on your teen.

When 16-year old Tanya Dunayvitser is at the mall, her mom knows.

"This blue dot shows me exactly where she is," says Larisa Dunayvitser, monitoring a map on the website telenav.net from home. "Exactly the time. Exactly location. Exactly."

Larisa Dunayvitser is tracking her daughter with a global positioning system embedded in Tanya's cell phone.

Tanya's initial reaction?

"I was not very happy at all," she laughs. "I could not get my privacy. She knew where I was going, everywhere. I don't like that very much."

But Tanya says she understands now.

"My mother explained everything to me and why she wanted it, and I guess I agreed with her," Tanya says. "It makes sense. I understand she wants me to be safe. It's fine."

The GPS cell phone tracking is a joint venture with Nextel and Telenav.

Nextel's Area Manager for Internet and Wireless Services is Andre Cunningham.

"What we've found is that in the last year and a half that we've had this, it's exploded on us," he says. "Here in the Puget Sound we've added well over a thousand customers in that year and a half time frame."

Most new customers are businesses tracking where workers are driving, even how fast they're going.

For now, families are just catching on to the technology.

And Tanya - who feels she's lost a little privacy - might get something else in return.

With renewed peace of mind, her mother says, "Maybe I will let her stay out longer now. I feel great. She's safe. I know where she is."