I found that I'm able to get the 100 MB download limit on cellular. I'm at work and went to download a game that gave me the message to wait and then I had to restart my iPhone and when it restarted, the game was downloaded. I do not have Wifi turned on and have never connected to a wifi network at my job before. To test, I went to download Apple's Numbers app. It gave me the error so I turned the iPhone off completely and back on and it downloaded over cellular.