I have an iPhone on the prepaid $15 base plan, with a data booster and a talk booster added. I have made a few calls (which are shown under Booster Usage when I log into self-serve) and sent and received some texts (which are free in my base plan), but I turned Cellular Data off as soon as I bought the phone two days ago, and have never turned it on. I've been using my home wi-fi network. And yet, sometime between last night and this morning, 0.01 MB of data was used. Yesterday evening, usage of my data booster showed zero when I logged into self-serve, and this morning it was 0.01 MB. How is that possible? Having seen the data usage when I checked my profile this morning, I double-checked that Cellular Data was still off on the phone, and as part of doing so I turned it on and then off again. It was on for only one or two seconds, and the phone was connected to my home wi-fi network at the time. Then I logged into self-serve and checked my data booster usage again, and now it's showing that I have used 0.02 MB! How can data be used when Cellular Data is off? And what could have happened in the two seconds that it was on to use another 0.01 MB? This isn't a lot of data use, but I want to know why it's happening and how to stop it.