updated 09:30 am EDT, Mon May 13, 2013
Does not require jailbreaking, doubles throughput rates
An altered carrier update that has been modified by two hackers successfully increases the bandwidth available for iPhone 5 units on T-Mobile's US network, tests have found. The patch to the carrier update file, which was originally distributed to add LTE signal to the iPhone 5 using T-Mobile's 1900MHz band, works on both unlocked AT&T units as well as "native" T-Mobile iPhone 5 devices without requiring a jailbreak, though instructions vary for customers using jailbroken iPhones.
The patch, first reported by TmoNews, comes after users who had installed the original T-Mobile update complained of slower performance and lesser signal after enabling the LTE capability and Visual Voicemail. Hackers @joe012594 and @cooldayr2 researched and developed the modified carrier file, which increases the bandwidth available by re-enabling DC-HSPA+ support.
The original carrier file set the HSPA+ band preference in the iPhones to AWS even if the iPhone model doesn't support it. The hack essentially resets the preference to "automatic," meaning iPhone 5 units will now switch between AWS and PCS depending on what is supported and which signal is stronger. Because the patched carrier file doesn't make any permanent changes to the iPhone OS, it can be installed by any iPhone 5 user on T-Mobile's network.
The instructions for installing the altered carrier file require completely resetting the iPhone, so a backup beforehand is strongly recommended. For un-jailbroken units, users then reset the network settings on the iPhone itself (Settings, General, Reset, Erase All Content and Settings), download the hacked carrier file, connect the iPhone to iTunes, decline any attempts to update the carrier settings, then open Terminal and type in an instruction to turn on the "carrier testing" mode. The instruction, seen below, varies for Windows 32-bit, Windows 64-bit and Mac users.
Following this, users then return to iTunes and click on the "Update" or "Check for Update" button on the device's main page in iTunes, while holding down the option key (Mac) or Shift key (Windows) and navigate to the custom carrier file that was downloaded, which is named TMobile_US_iPhone.ipcc. Once installed, a reboot of the iPhone 5 should fully enable the altered bandwidth, bringing a substantial speed and signal strength increase. Testing shows at least a doubling of effective throughput, with some results (depending on location and other factors) going much higher. Once complete, users may need to restore their iPhone.
The Terminal or command prompt instructions are as follows: for Windows 32-bit users, the command is cd "C:Program FilesiTunes" followed by the command iTunes.exe†/setPrefInt carrier-testing 1, paying attention to spaces in the command. For Windows 64-bit users, the commands are similar but slightly different: the first command would be cd "C:Program Files (x86)iTunes, followed by the same second command. Mac users would type the following into a Terminal window: defaults write com.apple.iTunes carrier-testing -bool true.
In the event that the patched file will not install or doesn't work, users can re-download the default file and go back to the way they had it with no difficulty. They simply repeat the above steps, only using the default file instead of the hacked one.
The procedure varies for those with jailbroken units, but is made somewhat easier by the use of an unofficial program called iFile. Users use the program to download the jailbroken version of the hacked carrier files, unarchive them and copy the file "overrides_N41_N42.pri" into var/mobile/Library/Carrier Bundles/TMobile_US.bundle and paste the file into that folder, overwriting the original .pri file. As above, to revert to the original carrier file simply follow the instructions again using the default file for jailbroken units.