Image: Cashier & customers at checkout © Andersen Ross, Getty Images

Related topics: debt, credit, credit card, smart phones, Melinda Fulmer

If you think U.S. consumers were huge impulse buyers before the recession, just wait: Mobile-phone companies, banks and credit-card companies want to speed things up so people can simply swipe their cell phone to pay for everything from cups of coffee to cruises.

Banks such as Citigroup and a technology startup, Bling Nation, which ties its tags to PayPal accounts, have in the last year launched radio-frequency identification (RFID) payment stickers to attach to your cell phone. They will allow customers to rack up charges without even carrying a wallet.

And over the next few years, companies including Apple, Samsung and Nokia will incorporate special near-field communications (NFC) chips in smart phones that will let shoppers make purchases simply by tapping their phone against a terminal - no sticker required.

Mobile analyst Leif-Olof Wallin of Gartner Research says he expects half of all mobile phones to have the chips by 2015, pushing this tap-and-go payment into the mainstream and getting us one step closer to using our phones in almost every aspect of our lives.

The downside of fast money

But while the mobile wallet sounds incredibly convenient, experts say it could pose a potentially big credit risk, especially to younger consumers who may swipe and forget -- and rack up big debt.

"There is certainly a disconnect when it comes to spending and using a credit card versus cash," says Bill Hardekopf, the CEO of LowCards.com and author of "The Credit Card Guidebook."

When you have to reach into your wallet and fork over several bills, write a check or even sign a credit-card receipt, you're closer to the financial pain, he says.

"Your mind says, 'Do I want to do this? Is this item worth it?'" But will that happen with something as painlessly quick as a swipe of the phone? Maybe not, he says.

Banks and other providers of this technology downplay this risk, saying it is just the next evolution in personal finance: Just as many of us have booted checkbooks from our wallets and purses, those old-fashioned plastic cards are the next thing on the way out.

"In five years, you're only going to need to think about your phone," says Mung-Ki Woo, the head of MasterCard's mobile payments division. "Everything else will be inside your phone, including your keys."

Revving up the spending machine

Why are credit-card companies and others so eager to get us paying with our phones? The answer is simple: We spend more.

While Citi and several other companies declined to say how much more mobile-payment users spent, market-research firm Forrester Research says that consumers who express interest in mobile payments spend 22% more on average than people not interested in it. And they were more likely to make frequent purchases.

When PayPal account holders were offered the chance to use its Bill Me Later credit service on eBay, the size of purchases doubled, says Anuj Nayar, PayPal's director of global communication.

The beginnings of a mobile revolution

The technology for this kind of swipe-and-go mobile payment has been in place for years, analysts say. It has already been used for public transportation and other types of purchases in Europe, Japan and South Korea.

But until last year, mobile payment in the U.S. was virtually nonexistent, outside some purchases made with a credit-card number on a smart-phone browser, or through applications from Amazon or eBay.

Fewer than 6% of U.S. adults online have used mobile payment, according to a report released last summer by Forrester. But, according to that report, 15% of adults are "interested" or "very interested" in using their mobile phone to pay for items in a store rather than whipping out plastic.

Enter Bling Nation, a Silicon Valley startup that partnered with PayPal last summer to provide payment tags for phones that are now being used in about a dozen cities in six states, mostly college towns.

Users of these tags simply affix them to the back of their phone and tap the phone on a piece of hardware at the retailer to pay. The purchase is subtracted from a linked PayPal account. A text message is sent to the phone user with the purchase amount and any relevant balance information. A paper copy is generated only if you ask. It also spits out coupons and sales information via text, to entice shoppers to come back.

It's a great way, says Bling co-Chief Executive Wenceslao Casares, for retailers to tailor the shopping experience for you -- and learn more about your spending habits and preferences along the way.

Tia Gao, an MBA student at Stanford University, says her trips to the local coffee shop have gone up in the past three months since she's started using the Bling tag and getting coupons from the shop on her mobile phone.

"I'm going more frequently because it's easier," she says, and the rewards are more immediate than with other types of payment. "I can go in, even if I'm running and don't have my wallet."

She says that convenience has -- at least initially -- made her spend more than she wanted to with Bling, but not enough to cause her stress. In fact, she says that ultimately she will be better able to track her expenses via Bling's Facebook app and text messages.

First adopters

Last year, MasterCard launched its own system of payment stickers that can be tapped on its PayPass terminals at 270,000 retailers, including CVS, Home Depot, Best Buy and McDonald's. No signature is needed for transactions under $50.

Since last June, its largest issuer of PayPass tags, Citigroup, has issued almost 300,000 tags to its credit-card account holders.

"It's been a huge success," Natalie Marin, a Citi spokeswoman, says of the tags, which are not available for Citi's debit accounts.

Are these stickers just the first and fleeting step in the move to a mobile wallet?

The real future of mobile payment, some say, lies with phones that contain embedded NFC chips that can beam and receive information at a distance of 4 inches. Nokia and Samsung already include swipe-and-go NFC chips on a few phones. Nokia has said these chips will be in all of its smart phones starting next year.

Apple is expected to incorporate NFC into the iPhone 5, which is expected this summer. With credit-card or other banking information already on file for a large number of iTunes users, analysts say, Apple could control a large chunk of this mobile purchasing power.

Indeed, 47% of Apple iPhone owners say they're interested in mobile payments, more than twice the proportion of online adults overall.

What's wrong with convenience?

For those who carefully track their expenses, set limits and protect their phone, the transition to mobile payments shouldn't pose any problems, analysts say.

But there is always the chance of fraud. Many people leave their phone lying around more casually than their wallet. If someone steals the phone and it has an automatic login, a thief could do some serious spending.

MasterCard's Woo says that banks can easily track a lost mobile phone and stop short unauthorized charging by disabling the application inside the phone. Most large purchases, analysts say, require use of a personal identification number.

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Still, Gartner's Wallin says there's a lot we don't know about how secure these payment systems are -- for instance, how easy it is to intercept NFC signals.

However, the biggest risk is just its accessibility and ease of use.

Gail Cunningham, the spokeswoman for the National Foundation for Credit Counseling, says her group always advises people that more plastic equals more temptation, so leave the cards at home. But in this case, she says, there's nothing to leave behind.

"No one's going to pull their phone out of their pocket and put it in the dresser drawer. This could be a potentially big problem for undisciplined spenders."