Maybe someday we'll all have contractless phones. And hopefully, we can all ditch preset plans for fluid ones that fit like a glove every month. We're not there yet, but a new service provider by the name of Zact is taking a big step in that direction. It's a beautiful glance into the smartphone future we all deserve.

Launching with pre-orders available today, Zact is a Mobile Virtual Network Operator (MVNO) that piggybacks on Sprint's network, joining the likes of Ting, Republic Wireless, and Boost Mobile. But what Zact brings to the table is a ridiculously granular amount of control over what you use and how you pay for it, thanks to a supercharged app.

Zact not only lets you control the amount of minutes, texts, and data allocated to your plan as the billing cycle trudges on, but actually lets you do it from inside an app on your phone. Even if you set it all to unlimited, Zact charges you only for the cheapest plan that includes what you actually use. And if you'd just rather set up limits for budget reasons, the app lets you scale your allowances up and down on the go to make sure you stay in the brackets you want. And if you decide you do want more minutes this month after all, you don't even have to put down the phone to get 'em.

Dynamic, pay-as-you-go plans aren't entirely new, but unlike any other provider we've ever seen, Zact actually lets you buy data specifically for use by certain kinds of apps. If you only use your data for Twitter, for example, you can buy unlimited Twitter data outside (or instead of) a normal data plan. And the same goes for email, or GPS. How well Zact can keep up with what new apps do what, and whether or not that's more cost effective than just buying a little all-purpose data remains to be seen, but the prospect is neat, and the flexibility is promising.

Zact also has a bunch of crazy data-sharing options. At the one extreme, you can share your whole plan and permissions to change it. At the other, you can set up sub-accounts and limit the amount of texts, minutes, and megabytes they can use. You can even set up use profiles that restrict app-use and other permissions based on the time of day, so that little Billy can only text you during school, or can't boot up any games after 9 PM.

But because Zact draws its customization power from an app that reaches pretty deep into your phone's OS, you're going to be stuck with some limited device choices. Unlike Ting, which supports almost all Sprint Android phones, or Republic Wireless, which only offers a single, pretty crappy handset, Zact is starting with two: the LG Viper 4g LTE and the LG Optimus Elite, both fully unlocked. Neither are top-of-the-line, but they come relatively cheap off-contract ($399 and $199 respectively) and theoretically Zact will be adding more, awesome-r ones to the stable as time goes on. And it should go without saying, but thanks to iOS, you're never going to be able to put an iPhone on this plan.

The lack of phone choice aside, Zact's approach sounds almost too good to be true, but really this is how buying stuff should be by default. Paying for only what you actually use shouldn't feel like some special deal you need to hunt down, and the options to narrow down exactly what you're ordering should be a given, not a bonus. It seems like an awesome setup, but the question is whether or not an idea like this can get from a scrappy MVNO to some of the game's real players. Here's to hoping, but not to holding your breath.