We’ve seen a number of companies attempting to shake up the wireless industry in recent months, from startups like Republic Wireless to established carriers like T-Mobile. This week a new player is throwing its hat on the ring with what’s probably the most flexible offering we’ve seen yet. Meet Zact.

An offshoot venture of parent company ItsOn, which is selling mobile plan customization tools to carriers as a cloud-based service, Zact builds on this strength to give subscribers the ability to set the number of monthly minutes, messages, and megabytes they want on individual plans or a pool of devices. There are no contracts involved, and users can buy as much or as little as needed, with whatever goes unused credited back to their accounts at the end of the month. They can also change their plan as often as they like right from their phones.

But the ridiculous amount of granular control over what you use doesn’t stop there.  For example, rather than buying a data plan you can buy access for specific apps at a lower cost. Or you could buy a small data plan and combine that with unlimited Facebook, mapping, email or whatever so that doesn’t count toward your limit.

If you are ever running low on minutes, messages or data, Zact will let you know so you can upgrade your monthly plan on the spot or buy a one time top-up. There will never be any overage charges and bill shocks since you’ll always know and agree to any changes made to your account.

A more detailed break down of the costs for plans is available here. To offer some perspective, the company says that the US average of 644 voice minutes, 764 texts, and 568MB of data would cost $37 per month.

Of course, there are a few caveats. Like other Mobile Virtual Network Operators (MVNO), Zact doesn’t own any spectrum or wireless infrastructure, and instead piggybacks on Sprint's network to provide wireless service -- which doesn’t have the best coverage or fastest speeds compared to T-Mobile, Verizon, and even AT&T.

The other bummer is handset availability. Zact is launching with only two devices under its belt, the LG Viper 4g LTE and Optimus Elite. Neither of them are top-of-the-line but they’re offered unlocked and relatively cheap at $399 and $199 respectively. More will be added eventually.

Even if you’re not sold on the new service, ItsOn is already testing its technology with four major carriers -- three in Europe and one in the U.S. -- so we may see some of Zact’s plan customization capabilities hit a major carrier at some point in the not-so-distant future. According to GigaOm, the company also noted that it has no plans to shut down Zact even if it proves successful selling its cloud policy service to carriers.