Carrier Cellular Data in use even though I'm in WiFi?

Is it possible that you lost WiFi even for a second and it used cellular data during that time. Cause 1mb of use kind of implies that.

 

In settings, I usually turn cellular off unless I need it.

 

I turn cellular on and off when I leave the house. Bit of a pain but I've read quite a few horror stories about people being charged huge amounts for data when their wifi goes down for a while and they fail to notice.

 

iOS doesn't have an always on WIFI option for cellular capable devices. When your iPad goes into deep sleep it will turn off wifi and revert to cellular. So you have to turn off cellular to force it to wifi only.

Windows Phone and Android both have always on wifi settings.

 

Isn't the cellular data used for the assisted GPS, even when on wifi?

 

Is this still an issue if no apps are allowed to run in the background? Is there anything for it to use data for in that case?

FWIW, I found that the amount of data that t-mobile was showing I used on my ipad when left on overnight (with apps allowed to run in the background) was substantially higher than what Verizon shows my iphone uses overnight, which is set up for all apps to run in the background and for push email on three accounts. But I only tested it for one night - after that I turned cellular off on the ipad.

 

No matter if you are using cellular or not your phone will "bark" at the closest cell tower every once in a while telling it that you are there.

 

From looking at inactive lines at AT&T and Verizon, I noticed that small amounts of data get used daily and add up to a couple of MB per month. Not sure what the data is for (probably sending all your personal info to the carrier, right? ) but it's possible that's happening with T-Mobile too.

 

Core apps like Mail, iMessage and anything that has notifications will still happen over whatever data connection iOS wants them to use.