Apple has always opposed jailbreaking or making any changes in the iPhones but after the current hack, they may change their mind. The folks from tmonews hacked the carrier update for T-mobile ,boosting the internet speed on iPhone by 3mbps to 8 mbps. The hacked update works on locked or unlocked iPhone 5 and also for unlocked AT&T iPhone mobiles.
The update set the band preference for HSPA+, even if your iPhone 5 doesn’t support it, to AWS which can cause conflictions and problems for the devices that don’t support that band.
For those with an iPhone 5 that supports AWS, this hack will also help you as well as it will connect to the strongest tower (PCS and AWS) rather than the preferred type of tower.
So,if you are on T-mobile and on 1900Mhz spectrum then get the update and enjoy the new speedy internet on your iPhone5. The update can be removed by installing the official carrier update.
Get the step by step instructions to get the update from tmonews.