My ATT bill shows data usage of 12+megabytes at 12:30am every morning. I have turned the phone off in the evening and turned it on at
8am and the data usage appears then i.e. at 8am. I am near WIFI at all times and data apparently does not use the WIFI. I have been told
that when iPhone is asleep that WIFI is not active and data defaults to cellular channel. The total data usage at these off times represents 10% of
my total data usage.
iPhone 5, iOS 8.4
I am pretty sure system services is the culprit. Now I wonder who uses all that data. For instance, who uses messaging data? I have looked through strings that discuss system services and no one seems to know who and why the data is used.
I Thank you for your help in researching my problem.
If System Services is it, then you would be able to see the data amounts for each of the areas listed there. Mine are all rather low, since I have Wi-Fi at home and at work both. It is just a bit when I am away that would be using cellular. You can take a screenshot of that and post if you like. I'll put my comparison here for you to look at. Remember, this will change after a reset based on what services are used. For example, if after I reset the statistics, if I didn't use Siri, there would not be an entry like that.
Data usage in your AT&T bill is not exactly representative of the actual time the data was used. This reflects the billing times. It is correct that when you are near Wi-Fi, if your phone goes to sleep, it will disconnect from the Wi-Fi as a power saving mode. If the phone is awakened, then it will immediately reconnect to Wi-Fi. The only difference for this is if you are connected to Wi-Fi and the device is connected to power. You can go into Setting>Cellular and look at the list of apps there and determine what apps may be using cellular data, and after resetting them, you can see how much each app is using within a particular time period.
To be honest, 20MB is not that large, but to find out what apps are using your data, use the information I provided earlier. The app will show how much data it has used since the last time you reset the statistics.
I checked the cellular data and found that it's all service statistics data that is the culprit. I also tried to leave the charger on the iPhone overnight to see if it would switch to WIFI during the evening. It didn't i.e. statistics data appeared under cellular data. You are correct that it's not a lot of data (roughly 5-10% of the total cellular data transferred) but it pushes very close to the 10 GB limit sometimes. Now that I know what is causing the cellular data, do you know what the statistics data is used for? Is it data used by ATT or is it "cloud" data? Are there any sources of information that would describe what statistics data is used for? The categories for my services usage include iTunes, messaging, push notification, networking, voicemail, time and location, mapping, cellular, documents and sync, and security.
Are you referring to System Services? If so, the listing there will show you the individual usage statistic. The next time your billing period ends, reset that statistic, and then you can check against your monthly usage. Or, you can reset at the beginning of a day and check at the end. Just for comparison, I reset mine on July 2 in the morning, and right now I show 19.7MB under System Service as of this afternoon.
TThank you Chris. That explains the mechanism. Do you have any knowledge of why the phone is initiating these large data transfers? They are of the order of 20 megabytes
ATT data at 12:30am when I am asleep
