AT&T iPhone users can hack their device if they want to improve their network’s performance. It does this because carriers normally use a specific, preferred band for your signal. This hack, however, will make your phone use the band giving off the strongest signal, which can improve connectivity.
Here’s how you can accomplish it on your iPhone 5:
1) Plug your iPhone 5 to perform a backup. If anything should go wrong, you’ll be glad you did.
2) You will also need the hacked carrier update, which is here.
3) You will want to enable iTunes to accept custom carrier bundles, which is explained here for both Windows and Mac:
64 bit:cd C:\Program Files (x86)\iTunesthen type: iTunes.exe/setPrefInt carrier-testing 1
32 bit: cd C:\Program Files\iTunesthen type: iTunes.exe/setPrefInt carrier-testing 1
Mac users you will need to open terminal and type the following and enter it in:
Mac: defaults write com.apple.iTunes carrier-testing -bool true
4) Go to your iPhone tab in iTunes and click “Update” or “Check for Update” while holding down Option (Mac) or Shift (Windows). Navigate to the hacked carrier file you saved earlier and select it.
The hack is also available for iPad. You can find the instructions for both tutorials at itweakiOS.