Evan Schuman's StorefrontBacktalk

The mobile wallet that Microsoft unveiled on June 20 turns out to be a radically unbundled approach, at least compared to Google Wallet and ISIS. The wallet app itself just collects individual issuing-bank and loyalty-card apps, while Microsoft is handing off responsibility for securing payment-card numbers to mobile carriers. It looks like Microsoft isn’t even touching transactions—which is good and bad news for retailers.

The good news: no Google-style POS changes required, at least not to meet Microsoft specs. The bad news: no help from Microsoft, either. Unless you build your own in-store shopping app, the Microsoft Wallet will basically do contactless card emulation—and not much more.

Microsoft has refused to answer any questions about the wallet, which is just one feature of the Windows Phone 8 operating system it expects to ship later this year. That suggests either there’s a lot Microsoft hasn’t figured out about how it will work or there’s a lot less here than you’d expect from a “mobile wallet.” Based on what the software giant has said, it looks like the answer is “less.”

For example, the wallet demo for developers last week was about 10 minutes out of a two-hour presentation. But that was time enough for Microsoft exec Joe Belfiore—manager of the Windows Phone Program—to explain that all the payment cards in the wallet were actually individual apps—for example, a Chase app for a Chase payment card, another Chase app for a debit card—bundled together with the wallet user interface. Nothing wrong with that, but it’s not something that will enable anyone to push the boundaries of CRM.

Microsoft also announced last week that using its phone for tap-to-pay will depend on having an NFC-enabled SIM from a mobile operator. Or in the words of the official announcement, “When paired with a secure SIM from your carrier, you can also pay for things with a tap of your phone at compatible checkout counters.”

Translation: The payment-card numbers will be stored in a Secure Element on the SIM. That means the mobile operators, not Microsoft, will control what cards go into the wallet, and that’s who card-issuing banks will have to deal with. (Will that involve ISIS or individual carriers’ own NFC efforts? At this point, no one is saying.)

From Microsoft’s perspective, that’s elegant—it makes card numbers somebody else’s problem, whether that’s getting them onto the SIM, changing or deleting them, or keeping them secure.

For retailers, it means there’s no Google or ISIS trying to figure out how to make money without adding to existing interchange fees. Microsoft will presumably make its money by selling phone software licenses.

But it does push some of the complexity directly onto large chains if they’d like to do something a little fancier.