Is there a tweak that lets me turn off the 4G chip? At work, the 4G signal is bad with my building, and wish to just go back to 3G signal. I would like to keep LTE on, because sometimes if I sit near the windows I have LTE. I am unsure if you can do that, but if there is a way to force the phone to 3G that is what I am looking for. Should say this is for an iphone 5s