The guys over at iTweakiOS have release a pair of cracked carrier updates for AT&T and Sprint that promise to bring faster speeds and better overall signals to iPhone. The updates don't require a jailbreak, but you'll need an iPhone 4S or iPhone 5 to take advantage of them.

The hacked update for Sprint is pretty simple, and promises improved data speeds over 3G. The Sprint update only work on the iPhone 4 though. The AT&T hack is a lot bigger, and on top of speed improvements, also adds HD Voice. Like previous hacks like this that we've seen for other networks, they're easy to install and work pretty well. I've had the AT&T one running on my phone for a couple days and have seen an improvement in reception, although it's debatable whether call quality is any better. Head over to the iTweakiOS page to install the updates for yourself.

NEW! Hacked AT&T Carrier Update for iPhone and iPad | iTweakiOS

Sprint Carrier Update Hack (iPhone 5 Only) | iTweakiOS