While it’s rare, sometimes developers are able to sneak features into their apps that don’t exactly comply with Apple’s policy.

At least this is true for FlashArmyKnife, an iOS app that allows you to circumvent carrier restrictions by enabling free tethering functionality. The app itself its basically a “Swiss Army Knife” that provides various utilities, like an advanced calculator, a satellite map, a currency converter, a battery power monitor, and more. The tethering function isn’t explicitly featured, so its understandable why Apple would miss it.

To access tethering, you’ll need to pull up the calculator function and type in the following equation, 1642, M+, C, 1452, M+, C, 1943, M+, reports iDownloadblog. (See demo video below.) The message “Run” should then pop up on the calculator pane, allowing you to get other devices online. The catch is that tethering requires you to create a bridge connection between your computer and the iPhone, which isn’t exactly an easy process for Windows users.

This kind of tethering functionality is barred from iOS apps because wireless carriers usually charge a monthly fee to enable internet sharing. Verizon and AT&T also still have some customers with unlimited data plans, which they clearly don’t want those subscribers abusing with tethering.

The app itself costs $2 in the App Store, but my guess is that Apple will soon have it yanked.