The iPhone 5 boasts Apple's most advanced cellular radio yet, able to do super-fast LTE on multiple carriers around the world, speedy DC-HSPA+ and HSPA+ on AT&T and GSM carriers, and slow EVDO rev. A on Sprint and Verizon. But how fast is fast?

We need your help to find out! Download the free app from the App Store, make sure you're not on Wi-Fi, and then run a few tests. Let us know where you are and how good your data speed is. If you can, post a screen-shot in in iPhone 5 speed test forum thread so we can get the exact results.

We're going to crowd source this to see which carriers, in what areas, are providing the best connections, and just how good Apple's new iPhone 5 is overall. (And yes, we want all the results, good, bad, and ugly!)

So grab the app, do the test, post the results, and share your screenshot now!

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