One of the features that Samsung showed to us on the launch of the Galaxy S5 was the Download Booster. This feature would allow the user to use both LTE and Wi-Fi connectivity at the same time to download a file faster.
Now, as the Galaxy S5 is launched all across U.S. carriers, 3 of 4 of the big carriers block this feature (T-Mobile is the only one to allow). Other minor carriers have also this feature, like U.S. Cellular.
The block of features isn’t new, with features like FaceTime or Video Chats in Hangouts being blocked in the past but let us hope that soon they change their mind. For the time being T-Mobile is available if you want this feature.