I've been rather curious about my iPhone 5 LTE speeds for a while now and even more so when I saw the iTweakiOS.com carrier hacks saying they improved the transfers and all this other oh please! features. So After I updated the carrier settings with the modified AT&T ipcc I wanted to see if I could really see a difference, which I didn't. it was just about the same. However, I was curious what the transfer rate would be while on a phone call. So I called up a customer service line (AT&T since they have the longest hold times ) and ran 10 consecutive times on the same server. My results were shocking I averaged out about 2.54 Mbps download. Now the Upload was the most shocking and obvious sign of there being something more than because I'm using the phone, with each test it was .06 Mbps up! Obviously there had to be some throttling over my data while using voice simultaneously. However, I couldn't prove it since I don't have another iPhone 5 with a carrier. Then I remembered that hey T-Mobile's iPhones can do voice and data at the same time, lets take a drive down there and see if they have the same LTE speeds and furthermore if they match or exceed the transfer rate as my AT&T iPhone 5 has. Long story short, T-mobile has a slightly faster LTE speed than AT&T in my area getting around 12-15 Mbps down and about 9 Mbps Up. But the real kicker is that after a slew of tests of using Voice and Data calling my AT&T phone from the T-Mobile phone and just pressing restart over and over. T-Mobile around 5 Mbps Down 4 Mbps Up AT&T 2 Mbps Down .06 Mbps Up There was some talking about iPhones and the T-Mobile service and I just asked to see what would happen if I put a T-Mobile Sim in my phone and all be damed, it registered the network, gave me LTE and the same results as the Offical T-Mobile phone. In short, AT&T is screwing me with my data speeds, but gave me a wonderfully unlocked iPhone 5 instead. Thank you for your time I just had to share that.