Just entered the 21st century, and was told that if I have wi-fi in home that my android phone can pick up the wi-fi and use that for internet/etc. and I wont be charged for using my limited data. How can I be certain that I am in fact using the wi-fi and not being charged/using my data allocation. While my data usage is minimal it seems I am using data from my allocation as opposed to "free" home wi-fi use. My phone does indicate that it is connected to my home WIFI.