Evan Schuman's StorefrontBacktalk

In fact, ISIS turns out to be a lot more vague in many areas than you might have thought. For example, when word of the ISIS alliance first leaked out last August, Sprint was conspicuously (and without explanation) absent. This week, however, a Sprint VP told Bloomberg News that Sprint was part of ISIS early on but withdrew to pursue its own plans.

(When was that? Probably sometime after the holding company for ISIS—it’s officially controlled by “JVL Ventures LLC,” which has addresses that happen to match those of Verizon corporate offices—started registering the ISIS trademarks in February 2010. Watch for services called “Vendi,” “Pivot” and “Proxi” to come from ISIS eventually, since the group trademarked those names at the same time.)

Then there’s Discover, which is currently slated to develop the payments network for ISIS’ Salt Lake City project. Last November, ISIS members worked hard to make clear that Discover was the only payment-card provider for ISIS. That, it turns out, is true—for the moment. But one industry source pointed out that, whatever impression has been left, no one on any side has actually said that ISIS and Discover have an exclusive deal. But they certainly went out of their way to let analysts and reporters jump to that conclusion—and didn’t correct them when they did.

There’s one thing ISIS is clear on, though: The mobile operators won’t be putting customers’ purchases on their monthly phone bills. That may be the most baffling thing in the whole ISIS puzzle.

Mobile operators have two advantages over other players trying to make it in mobile payments. First, a mobile operator can authenticate a customer, and already does that every time the customer makes a phone call. That should be a big advantage, because fraud is one of the biggest challenges in any scheme to replace payment cards.

Second, a mobile operator already has a billing system that all its customers are using. That’s the other big challenge for anyone who wants to cut Visa, MasterCard and other payment-card companies out of the loop—and that, in turn, is the only way to cut interchange fees, which is the most attractive reason for retailers to get on board with any true mobile-payments system.

Trouble is, a true mobile-payments system is hard to do. It would require rebuilding the entire loop, from the phone to the POS to the retailer’s back-end software to the payments processor and, finally, to the billing system. That’s why most of the players in mobile payments aren’t trying to do that. Instead, they’re just trying to get phones equipped with near field communication (NFC) chips to emulate contactless payment cards, so most of the existing payment-card loop remains intact.