Why do I have mysterious cellular data usage (Verizon) every 6 hours on all 3 of my iphone 5's?

I have recently uncovered mysterious cellular usage on three different iPhones. I am a Verizon customer and discovered this by examining the cellular data use logs. What I found are a long series of mysterious data usage logs. I have visited the Genius Bar at my local Apple Store 3 times now to log notes and discuss the issue. It is being escalated.


The characterstics are as follows:

  • All my family phones have the appropriate IOS and hardware updates (verified by the GeniusBar at my local Apple Store).
  • This is occuring across three phones, which happen to all be iphone 5. Two are 5 and the other a new 5s. We do have one iphone 4 in the family but the issue (so far as I can tell), is not happening on it.
  • One iphone 5 has IOS 7, the other IOS 6. The new 5s has of course IOS 7.
  • Mysterious data use happens even while connected to wifi.
  • Each mysterious data use log entry is exactly 6 hours apart. For example: 2:18 AM, 8:18 AM, 2:18 PM, 8:18 PM, 2:18 AM ... etc. It cycles AM and PM, same times, for a day to many days until some condition causes it to change (evolve).
  • The times evolve. One day it could be cycling through at one time series, then it changes to another time sequence and continues until the next condition.
  • The data usage is anywhere from a few K to many MB. The largest I've seen is over 100 MB.
  • The logs clearly show these usages are not due to human interaction. It is a program.
  • If cellular connection is used frequently (by the owner), the pattern is hard to pick out. Luckily, my family member is very good about only using wifi whenever possible, so these mysterious use patterns are easy to pick out.
  • Verizon allows access to 90 days worth of data logs, so I downloaded and analyzed them. This has been happening for at least 90 days. I have found 298 instances of mysterious use out of 500 total connections to cellular. A total of 3.5 GB of mysterious cellular data has been recorded as used in that 90 days by this phone alone. Only .6 GB of the total cellular data use is legitimate, meaning by the person.
  • This issue is occuring across three different phones. Two are iPhone 5, and the third is a recently purchased iPhone 5s. The 5s I have not touched beyone the basic startup. I have left it alone on a desk for 3 days, and looking at the logs, the mysterious data use in the same pattern is occuring.


So ... I am speaking to both sides, Verizon and Apple to get answers. Verizon puts their wall up at data usage. It doesn't matter how it is being used, you simply need to pay for it. Yes, the evidence I have gathered is getting closer to someting on Verizon's end.


Before pressing in that direction, I am hoping someone reading this may recognize this issue as a possible iPhone 5 issue ... OR ... you, right now, go look at your data usage logs available through your carrier's web account, and see if you can pick out a pattern of mysterious use. Look especially at the early morning instances when you are most likely sleeping.


I am hoping this is a simple issue that has a quick resolution. I'm looking for the "ooohhh, I see that now ..." But I am starting to think this might be much bigger, but the fact is, most customers rarely or never look at their data usage details, much less discover mysterious use patterns.


The final interesting (maybe frightening part) thing about all this is that I discovered while talking to Verizon ... they do not divulge which direction the data is going. This goes for any use, mysterious or legitimate. Is cellular data coming to your phone, or leaving it? Is something pulling data from your phone? We know that it is possible to build malware apps, but the catch with my issue is that it is also happening on a brand new iphone 5s with nothing downloaded to it.


Thanks for your time

iPhone 5, iphone 5 and 5c, both ios 6 and 7

Posted on Oct 28, 2013 10:20 AM

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Question marked as Top-ranking reply

Posted on Jan 23, 2014 10:59 AM

mtamaki wrote:



Other questions from a while back in the disucssion -


  1. Which way is the data going, push or pull?
  2. Why does it use cellular data only and not wifi when it is within a strong wifi network? The 6 hour increment of data use does stop when you turn off cellular data.
  3. What on the iPhone, even it were service oriented, requires that much data? Ideas may include documents, email, pictures, video, application data, facetime video and sound ... etc

1. No way to know which way it is going, unless you have an app such as Onavo. However, Settings/Cellular shows cumulatively how much data was sent and how much was received.


2. Being within a WiFi field is not sufficient. WiFi goes off 30 seconds after the screen goes off to save battery, so any data transfer when the screen is off will go over cellular. WiFi, unlike cellular, uses power continuously, whether transferring data or not. This is not an iPhone characteristic; it is the nature of the WiFi standard. But it means that if WiFi stayed on all the time the battery would run down very fast. The exception is when the phone is connected to power. Then WiFi stays on.


3. Settings/Cellular will show you how much data each app uses, but not what the app is using it for. You can turn off individual apps to prevent them from using cellular data. If you take frequent screen shots of that page you can sort of graph your data usage for each app over time.


Regarding the 6 hours, it's more complicated than I implied. (I've worked on telecom billing systems). Whenever you leave one area covered by a Mobile Telephone Switching Office (MTSO) that switch sends a single record to the billing system showing all of the data you used while connected to the switch. These occur at random times. (An MTSO can support many towers, so it is a larger scale than simply a tower). The systems I worked on also had a "close" function at the end of the day that sent a single billing record from the MTSO you are connected to at the close time, which is roughly midnight PST for AT&T. This is so if you stay home for several days you get a summary record each day rather that one after multiple days. Many other carriers around the world use the same billing system.


Verizon uses a different billing system. I'm guessing here, because I never worked on Verizon's system, but since the 6 hour interval is so consistent I suspect that Verizon's MTSOs send the summary record from the MTSO you have been connected to every 6 hours rather than every 24 hours. The reason you see other usage in between is due to the fact that as you travel when you leave the coverage area of an MTSO a summary is generated also. And sometimes you can even switch MTSOs without moving; for example, if your local switch is overloaded you might be transferred to another nearby switch. This is especially common in large cities, where a switch may cover only a few blocks, as opposed to a rural network when the switches can be 15 miles apart.


On a historical note, when AT&T and Apple released the first iPhone a billing record was generated for every data transfer. This resulted in users getting bills of 300 or more pages, listing every transfer. Also, since the record only reported in kilobyte chunks, a 100 byte transfer would be reported as 1 KB. As data was unlimited for the first iPhone this usage inflation on the bill was not a problem for the customer, but it did make people wonder where all that information was going.

97 replies

Sep 17, 2014 1:36 PM in response to mtamaki

Here's the problem: Data Plan w/ AT&T and Verizon. I am just fed up with having to watch how much data i (and the rest of my family) am using and what is available before billing cycle ends. Once my contract ends with Verizon, I will be looking for Unlimited Data (Sprint). Trust me guys, its not your phones. My son has an iPhone 4 and I have an HTC Android (everything above applies).

Sep 25, 2014 8:17 AM in response to stlusch

I am convinced that the main culprit is the Background App Refresh. With a little experimenting I went from a mysterious 300+mb usage a day (broken up into the previously stated 6 hour download increments) to approximately 30mb a day, the reduction was linked to turning off the Background App Refresh. Try it, so far it has helped by diminishing my mysterious data usage.

Feb 5, 2015 4:29 PM in response to mtamaki

I believe I have the same issue with AT&T. 2 of the users on my plan just upgraded to iPhone 5 S and the data usage on these phones increased dramatically. Both had the Background App Refresh on for Face Book, Snap Chat, and Instagram activated and both show the huge data uses at regular intervals even when the phones were connected to wifi. The users turned this Background App Refresh off today so I'll look at the usage tomorrow to verify the reduction of the data usage.

Feb 5, 2015 4:54 PM in response to mtamaki

I have been using a mobile broadband modem since 2010 and I have never figured out what's using my data plan. Apparently Apple Mail and iCloud are big contributors. I have Mail, Calendar, and Notes using iCloud so my iPhone 4 will sync. I've noticed that a lot of the excessive usage is uplink, not downlink as I had expected. Facebook is a data hog as well. I'm struggling to stay within a 16GB data plan and I don't stream movies or music, I don't play games, and I haven't updated anything in months. I do keep the firewall enabled on my computer, phone, and mobile broadband modem. I would love to hear something from Apple about this.

Sep 11, 2015 5:23 PM in response to reet

I believe I'll be following suit with respect to turning off LTE - it does decrease battery use, but it's not worth it if it's the reason I allegedly chew through ridiculous amounts of data with minimal use. (Not to mention that sometimes turning off LTE is the only way I can get reception.)


This may be completely unrelated, but I've noticed that when I create a hotspot and work on my laptop over USB, I'm dinged for much less data even when going to the same sites I normally visit. I can understand that some of this would be due to AdBlock on my laptop, but we're talking an order of magnitude here.

Oct 12, 2015 9:56 AM in response to mtamaki

The 6 hour intervals are the data session the network allows you to carry on - your phone connects to cell tower and attaches to an available data port (not proper term, but I think you can understand that) that session will hold for six hours before timing out and starting another data session. You may not be using data nonstop for that six hours, but the ability is there if you need it. Push notifications kinda keep the session from going idle. Hope that helps

Jan 2, 2016 4:16 PM in response to mtamaki

I noticed mysterious data usage (approx. 1.2 GB) in last 4 days, when most part of this duration our iPhones had Wi-Fi connections. I contacted Verizon Wireless and inquired about this mysterious usage. Immediately the agent recognized the issue and told me that Wi-Fi Assist feature on the iPhone is the culprit, hence she recommended me to turn off Wi-Fi Assist feature, Settings>Cellular>Wi-Fi Assist (Scroll to the bottom on the Cellular window to reach Wi-Fi Assist switch).


In addition to her suggestion, I've turned off Background App Refresh switch on those apps which were consuming large amount of data. Hope these 2 changes will fix high data usage issue. I’ll post an update later for results.

Jan 2, 2016 4:18 PM in response to meyoda

meyoda wrote:


I noticed mysterious data usage (approx. 1.2 GB) in last 4 days, when most part of this duration our iPhones had Wi-Fi connections. I contacted Verizon Wireless and inquired about this mysterious usage. Immediately the agent recognized the issue and told me that Wi-Fi Assist feature on the iPhone is the culprit, hence she recommended me to turn off Wi-Fi Assist feature, Settings>Cellular>Wi-Fi Assist (Scroll to the bottom on the Cellular window to reach Wi-Fi Assist switch).


In addition to her suggestion, I've turned off Background App Refresh switch on those apps which were consuming large amount of data. Hope these 2 changes will fix high data usage issue. I’ll post an update later for results.

The other thing to be aware of is WiFi is turned off when the phone goes to sleep, unless it is connected to power. So background processing when the phone is asleep will always use cellular data (unless plugged in).

Jun 30, 2017 7:07 PM in response to mtamaki

It's happening on my iPhone 6, a 6S and a 7 in my family. I'm concerned thats it's verizon "polling" the phones and increasing data usage. Every time I talk to them they suggest the unlimited plan- - which leads me to believe it's a marketing ploy.


The last technical support person I talked to seemed to think it's something on their end and has promised to get back to me about the issue, although my past experience with Verizon is that it isn't going to help....

Jul 1, 2017 7:27 AM in response to beancter

Actually, that IS it. When you travel from tower to tower each time you change the tower that you have just used sends data to billing. That's the data you see between the 6 hour intervals. The 6 hour report is for the site you are connected to currently. I've designed phone billing systems, and they are all similar. AT&T users a once-a-day update at 12 AM PST for the current switch reporting, Verizon uses 6 hour intervals for the current switch reporting.

Jul 1, 2017 2:10 PM in response to beancter

beancter wrote:


then why did verizon tell me that's not what it is? they said its malware -- which I don't believe. and why doesn't it occur on every line in our plan?

Verizon didn't tell you anything. A Verizon tier 1 CSR, probably in India, and paid $1 an hour, told you that. The don't know much other than what is in their script. And they are rated on how many calls they can complete in an hour, so they will say anything that will get you to hang up. The average tier 1 CSR is in the job for 3 to 6 months before they move on. There is no malware on an unjailbroken iPhone, so you are right not to believe it.


You said it DID occur on every line in your plan:


Nope, that's not it -- there are numerous incidents of data usage between these 6 hour time periods on several of the phones. It's only the phones with low data usage that it's so easy to see between the six hour intervals. But on the line with a lot of data usage, those every six hour postings are still there, you just have to look for them.

It won't appear on any phone that has had no data usage.

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Why do I have mysterious cellular data usage (Verizon) every 6 hours on all 3 of my iphone 5's?

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