"If I can get the same service for less than half the money I'm going for it," she says.

Tiffany got a prepaid Droid which includes: Unlimited texting, internet and phone calls for $40/month! Her old 'contract based carrier' bill was about $100/month for the same services and benefits. The $60/month savings was such a good deal, she got her son, Ryan, a prepaid smartphone too, which he uses to surf the web.

"Since there's 8 of us, um, 8 people in my family someone's almost always using the computer," Ryan says.

We found the prepaid smartphone market is ringing off the hook! Sales more than tripled over the past year. Customers ditching those annual contracts are now one of the fastest growing smartphone segments in the U.S. With prepaid mobile you don't make any contract commitments to one carrier, and you pay a set flat monthly fee upfront--that eliminates any surprise

overage charges, which may be handy with tweens.

John Breyault is with the National Consumers League. He says, "You wouldn't want to give them a high end smartphone with an expensive post paid plan where they might get overages on and blow out your family budget."

The newest news to hit the prepaid market: iPhones! Now two cellular providers, Virgin Mobile and Leap-Cricket announced they're offering prepaid iPhone service.

And Larry Petrone with T-Mobile says if you currently have an iphone, ask your carrier to unlock it, bring it to their store, they'll pop in a new sim card and you can get inexpensive prepaid service.

"Often those customers find even with a penalty to cancel a contract they're able to save money by switching," Petrone says.

Some drawbacks to having contract-free cell service. If you want a smartphone, you'll pay the entire retail cost of the device, which can be more than $500 in some cases. Very few prepaid family plans are available, so you really need to figure out the savings for your household.

"You have to incorporate the higher upfront cost of the device itself versus the cost of keeping, adding another line to your family plan," Breyault says.

Even though Tiffany had to pay full price for two new smartphones, she says she's still coming out ahead. "I don't think I'll ever go back to using a contract service again."

One analyst says right now the prepaid market is primarily younger, less affluent users, who are 'highly mobile' and 'live' on their smartphones.