Here is why it was released for those that do not know. Along with iPhone 3.1.2, AT&T users received a 5.6 carrier file update, but the reason(s) for it werent clear. MMS was already enabled, and tethering was nowhere in site, so what was it for? Well, Turns out, it fixed an MMS bug: When sending photos or videos in an MMS message, the progress bar would stall at about 90% then result in an error ending with a (!) red exclamation point next to the MMS message. The associated message failed to be properly sent, though standard text messages worked as normal. The 5.6 patch addressed that particular MMS issue.