This could improve network performance for some users. Here's how it works:
This hack enables Release 9 DC-HSPA+ on the iPhone 5 and iPad 3, 4, and mini as well as enhancing LTE data and signal. Though AT&T is limited to HSPA+ 21, the device itself becomes more open to an increased amount of bandwidth thus allowing for better throughput of data and data connection. This is very convinient for users in areas that don't yet have LTE coverage. This hack also includes a fix to any and all iPhone 5 users who have experienced degraded/weakened signal over the past couple to few months on the PCS 1900MHz and/or CLR 850MHz bands for HSPA+ as well as the APT 700MHz and/or AWS 1700MHz band for LTE.
The issue was due in part to the newer revised iPhone 5's that came with the AWS band enabled for HSPA+, if you were to ever choose to leave AT&T for T-Mobile. It set the band preference for HSPA+ to CLR and LTE to APT which can cause conflictions and problems when you're in an area with towers on different bands with stronger signal. The setting has been set back to the default “auto” setting and should help the 4G HSPA+/LTE signal perform a bit better, whether your iPhone 5 is the older edition or the revised edition. This hack will also help you connect to the strongest tower rather than the preferred type of tower, whether on HSPA+ or LTE.
More details and instructions on how to install the hacked carrier update can be found at the link below...