Unknown data usage early morning

I have a similar problem: IPhone 4S (upgraded to IOS 6 OTA) connects to cellular data while sleeping/locked. I have an Airport base station the phone connects to when awake, but at night it's using cellular data.

My second iPhone 4S upgraded to IOS 6 using iTunes shows no problem.

All iPhones on every version of iOS have always disconnected from WiFi when locked, unless connected to power. If a data connection is needed while locked all iPhones have always used cellular data. This is nothing new.

Lawrence,

Here are Apple' notes for the iPhone 5 update (4s has same issue introduced by IOS 6):

"This carrier settings update resolves an issue in which, under certain circumstances, iPhone 5 may use Verizon cellular data while the phone is connected to a Wi-Fi network. "

I am not wrong. The iPhone has always turned off WiFi when the phone is asleep to preserve battery, unless it is plugged in. If you go back and read this thread (and other threads going back 5 years) you will find many discussions on this subject. The fix that was pushed yesterday was NOT from Apple, it was from Verizon, and it fixed a DIFFERENT problem of the iPhone using cellular data when the phone was not asleep and was connected to WiFi.

Lawrence is 100% correct. A few minutes with Google will show you that the iPhone switches WiFi off when sleeping and not plugged in, and has done so for years. The Verizon patch resolves an issue where Cellular Data was being used when the user was actually doing things on their phone and connected to WiFi.

Here is another data leak that while small on a daily basis, can add megabytes to your monthly usage and that could be enough to break your data plan cap. The problem is Apple Push Notifications (APN). It is well documented from Apple that APNs will ALWAYS use cellular over Wifi if cellular is available. The ONLY ways to stop this behavior is to shut off the cellular side of the iphone or turn off push notifications. DataMan Pro (I am a longtime user) showed that it was push notifications that were leaking data every hour by the same amount that ATT was showing in their usage records.

This is a legitimate data usage as it is an app on the iphone that is using the data, even though it is an app that we don't think about. Why Apple chose to prioritize cellular over WiFi for this particular feature is unknown, but we need to PUSH on Apple to reverse the priority.

With capped data plans quickly becoming the norm, we need to track down and kill every data leak we can if expect to not be surprised!

David T.

drtidmore wrote:

Why Apple chose to prioritize cellular over WiFi for this particular feature is unknown, but we need to PUSH on Apple to reverse the priority.

Why Apple chose to use cellular for Push notifications is well known, at least to people who understand the technology. Only cellular has the technical capability of pushing data. You cannot push over a WiFi connection, unless there is a process waiting for the data on the phone, running continuously (polling). Which would run down the battery in a few hours. Cellular data is capable of generating a "signal" that will wake up a sleeping process on the phone. Apple did it the only way that will work. However, the push signal just wakes up a process, the process then launches the app, and the app retrieves the data.

The amount of data transmitted by the Push notification itself is unmeasurable, a few bytes. If the phone is asleep when the push notification is received the app that retrieves the data will use cellular data rather than WiFi, for the reason repeated ad nauseam in this thread; WiFi is turned off to preserve battery when the phone is asleep. Some apps have a setting that disables Push data retrieval on Cellular data. That's up to the app programmer.

That is all fine and good, but after waking up the process to handle the push notification, when the phone is plugged in and has WiFi available, why not select WiFi over cellular, even if the iphone is in a locked state (such as overnight)?

Lawrence,

But it is NOT doing that. Apple states in support doc TS4264 that APN will always use cellular over WiFi unless it is unable to make the connection via cellular. I have logs from DataMan Pro as well as ATT usage logs showing that APN is sticking to the cellular side even when the phone is plugged in and there is WiFi available.

David

He's wrong to say it is new with iOS 6. I have had an iPhone since the first day they were available, and I have done network tests that verify that WiFi is turned off when the phone goes to sleep, approximately 45 seconds after it goes to sleep, to be exact. It's an easy test:

Go to your router's control panel and check the IP address of the phone, or get it from the WiFi settings on your phone.

Open a command window on your computer and type:

ping -t <phone's IP address>

You will see a continuing stream of responses. Now put the phone to sleep. The responses will continue for about 45 seconds, then will time out.

I've done this with every version of iOS since I noticed that I was using cellular data when I thought WiFi was on; that includes all versions of 3, 4, 5, and now 6.

Hi Lawrence,

You helped me understand a few things so far! Can you help me with this issue:

Is there an app that will show data usage for specific apps? I'm curious to find out which app xfered 5 MB yesterday morning when my phone was locked and I was sleeping. DataMan Pro did this but is no longer available. Of course I know I can't look into the past but to be able to log/monitor this in the future will help my OCD.

--

Asher

Apple doesn't allow apps access to the system functions that would be required to track data use by app, because that capability could be used by apps to spy on other apps or on you. The closest that you can get to this capability is Onavo, which routes your data through their servers so it can do data compression. It also tracks the data for each app that it supports.

Onavo also interferes with the normal operation of some functions, such as the WiFi hotspot capability.

RE:"Cellular usage even when there is Wifi"

I really hope in apple's wisdom it is not using a speed or reliability test to determine if it's on wifi vs 3G or 4G or LTE.. because that will be dumb. At current rates users are gettign faster speeds on LTE than their wifi and so if a speed test is used to determine the "better" connection, then wifi is not going to be used.

I really hope i am wrong cause this would be a HUGE over site.

its software related and has apperentlich something to do with your router... which make some how no sense, as my ipad3 works fine on ios6 and home network (slow really slow tho) but my iphone 5 doesnt... used 2.1 gb in 6 days 😝 inform ur carrier about that problem, as apple hasn't acknowledge it yet officially for eveyone (verizon excluded)

Hey, just caught onto this thread, I have started having these issues in the past month. My IPhone's average usage per month in the first 35 months i had a contract with this company was 124mb a month (1gb a month package). In the past month, since I had updated to IOS 6, i had the past month of 3.38 gb of data, with the data collection for the day showing between 11mb and 567mb in a day where i do nothing but listen to music and text.

I am not saying that this is IOS 6, just that this is when it started for me, and i have factory reset my phone, and disabled many options to no avail. To anyone that has this issue in Canada like myself, I am with Telus.

Just was curious if anyone had any information that may differ to my company from the AT&T, Verizon and other non Canadian companies. Thank you.