Well I received my replacement phone on Tuesday at noon and the issue has not appeared yet. I believe something was wrong with the phone I first received from my pre-order.
I have been using my replacement phone for over two weeks and the issue has not returned. Samsung and Tmobile tried to resolve the issue but in my case the phone had to be replaced. All the suggestions in this thread were tried and more. I believe the issue is a defect in some of the phones. If you have tried everything then I suggest you get a replacement. Tmobile ordered my replacement, I received a text when it arrived at the store and I swapped out the phones. I suggest you do not let them transfer your settings from the old phone to the new one. So copy all your data to the SD cards. That means check your games and apps for local files on the phone's memory. Be ready to reenter your login names and passwords in your apps. Once you connect to your Google account in the play store then you can download your apps again.
I'm having the same issue. I'm on the Verizon network, so apparently can't be blamed on a network specific issue. I'm a long time Samsung user and have never encountered this issue in previous phones. First realized it was happening when I received notice from Verizon that my data usage was reaching limit. Troubling that first reactions from Samsung seems to place problem on user (blaming user network, equipment) or personal settings. I expect more from Samsung. Hope this gets vetted, objectively, by Samsung.