We have 2 S4 phones at work. They spend most of their time connected to WiFi. On thumbing through my phone today I noticed it was showing 6.45 GB used last month (August). Seemed a bit high though we notice a blip earlier in the month when an android update was pushed to both phones, but that was under a gig. Here's the weird thing. Drilling down into the logs I found my phone recorded 4 GB of wifi traffic in one hour. 3-4pm on August 28 to be precise. My partner checked his phone - same thing! Here's the weirder thing. The ISP logs don't show any abnormal usage for that period or any other period, i.e. the high data usage was internal to our wifi. Our conclusion is that the phones were plotting with each other over the wifi. We were experimenting with tap-and-transfer between the phones but nothing like that amount of data. Is there anything I should know about unsolicited wifi transfers between S4's?