PHILADELPHIA (KYW) It is 11 o'clock and your teen is not home. The following day your co-worker is late for an important meeting. They could be anywhere but you can find them with location-finding phones. Ukee Washington has details on tracking technology.

Such technology is exploding onto the market. In fact, by next year alone an estimated 42 million Americans will be able to say: "I know where you are!"

Nikki and Tom Pratt don't need to worry about where their children might be anymore.

"I can just, at any time, see where they are," she stated, adding "What I like best is peace of mind. I'm comfortable, I know where they are."

How? Their kids carry cell phones equipped with the latest technology. Using a satellite driven service called uLocate they can see their kids' exact location on a cell phone screen or computer map.

"I know if I forget to call them, they at least they know where I am," said their son Jason.

AT&T Wireless has a similar service called "Find Friends." It lets you dial up the general whereabouts of other users but the system isn't based on satellite information. It uses cell tower location.

Travis Larson represents the Cellular Telecommunications & Internet Association: "So far, they're proving popular with families, with people who may want to know where they are in an emergency."

Parents aren't the only ones interested in this service. Businesses are getting in on the action and some privacy experts like Chris Hoofnagle of the Electronic Privacy Information Center worry about how the technology could be used by law enforcement, angry spouses, and even marketers.

"You could walk by a coffee store and that coffee store might be able to send you a text message and it might say, '30- percent off coffee if you come in right now.' But, you can imagine what this could be like on a broader scale," he explained.

There are no government guidelines for tracking cell phones but companies say they do take privacy seriously. With uLocate, your phone shows you when you're being tracked and at AT&T you must give permission to allow someone to find you.

(MMIV, CBS Broadcasting Inc., All Rights Reserved.)