Should you pay by smart phone with the new app for AT&T, T-Mobile, and Verizon Wireless?

Consumer Reports readers know what products they want, and so-called "mobile wallets" aren't one of them—at least for now.

This fall, when we asked 57,533 readers whether they'd used their cell phone to pay for purchases at a retail store, a resounding 94 percent said no. And that's not because mobile wallets aren't available. Big-name Google Wallet has been on the market for two years now. Square Wallet is also out there.

We hear you: Why go through the extra hassle of paying cashiers via smart phone when you can pay in the blink of an eye by simply swiping your old-technology plastic debit, credit, or prepaid card?

Nevertheless, three of the biggest cellular service providers think you don't get it. AT&T, T-Mobile, and Verizon Wireless, who usually compete with each other, are now working together to push the ISIS Mobile Wallet app, and last week they launched it nationwide, after two years of test marketing in Austin, Texas, and Salt Lake City.

So we asked the ISIS people why their mobile wallet is a better mousetrap. Unfortunately, ISIS hasn't solved the basic problems that have kept mobile wallets not quite ready for prime time.

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The first problem is that ISIS doesn't work on Apple iPhones. "We haven't announced a timeline yet, but it's coming," Jamie Johnson, head of marketing for ISIS, said. So you need an ISIS-compatible Android phone equipped with near-field communications (NFC) technology, which allows the phone to communicate wirelessly with a contactless reader linked to a retail store's cash register.

Luckily, about 40 popular phones qualify, including the HTC Droid DNA and Incredible; LG Escape and Optimus G; Motorola Droid Maxx, Mini, and Razr, and Samsung Galaxy Note II, Note 3, S III, and S 4.

Next, you need to travel to your carrier's retail store to fetch additional hardware, a SIM card with a "secure element" for storing your sensitive personal financial data. The SIM card is free.

Once you're up and running, you can add credit cards from only two banks directly onto the app, the American Express Green Card and the Chase Freedom, Sapphire, and Slate and J.P. Morgan Palladium cards.

You can use your other payment cards—but first you must get an American Express Serve prepaid card, which is also free. You then have to load money from your debit or credit card onto Serve, then use Serve on the ISIS app to finance your purchase. Very clunky.

Finally, you can use ISIS only at retailers who accept contactless payments. That's about 200,000 locations, according to Verizon, considerably less than the millions where you can use ordinary plastic. That means you must still carry your old cards to make payments everywhere else in the world—and when your phone's battery runs out of juice.

So ISIS requires a lot of stick-to-itiveness. That's probably why the promoters have to tempt consumers with incentives to use it. But even these are a chore: To collect three free Coca-Cola soft drinks, you need to hunt for an NFC-enabled vending machine and load the My Coke Rewards app onto your phone. But we couldn't find an NFC Coke machine locator online.

To get another incentive, 20 percent back for ISIS transactions using the Serve card (up to $200 in statement credits for purchases made through Jan. 31, 2014), you need to find and shop at retailers that accept American Express contactless payments. The ISIS website gives no clue where those locations are, nor could we find an online directory. But it's easy enough to find a participating Jamba Juice, where you can get one free smoothie per day when you pay with ISIS, until one million have been given away.

Bottom line: ISIS needs to build a simpler mousetrap.

—Jeff Blyskal

On Nov. 19, we corrected this article to report that there is no fee for getting a Serve card when used with ISIS.