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

I don't think this is anything specific to your carrier, or your iPhone 5. We have an iPhone 4 running on Tesco Mobile UK and that also transmits data every 6 hours. It looks like it's uploading the phone's usage statistics to the carrier, dates & times of SMS, calls, numbers called, data usage etc. so that everything is nicely itemised when we look at our online bill/statement.I'm not sure if my android phone behaves the same (i.e every 6 hours) as I can't tell because i use plenty of data. The iPhone 4 is locked-down so no apps are available to use data, although the data connection is enabled. That's how we can clearly see the 6-hourly upload, i.e. 04:33, 10:33, 14:32, 20:32 etc...

So, i think the size of the uploaded data may depend on how many calls & SMS you send - if you send 100 SMS over a few hours, each SMS is logged as: DATE - TIME - NUMBER SENT TO - TYPE - CHARGE. So 100 entries like that could take 100 x 50bytes. Multiply that over the whole day and then include all of your call logs and data usage logs, depending on how well they manage the uploaded data packet explains why some people see unexpected data usage.

For me, this uploading of data shouldn't be charged to the users data allowance. Yes, it's using the data, but we're not the ones actually using it.

Take a look at your on-line usage (if you have access) - all that data has to get there somehow!

Why would the carrier need that information from your phone when the SMS or phone call went through the carrier's system? The carrier already has the information and getting such information, again, from the phone is silly.

I really don't know. I'm not saying that they are the only things that are being uploaded. Knowing Apple, there are probably other things that are being verified, such as IMEI numbers of phones that are on contract. There are also their things that may be getting 'checked' on a 6-hourly schedule - mail, App Store checking for updates, podcasts (check this one), location services updating etc. etc. I've a feeling that 6 hours is a common setting for checking mail, or syncing of some sort. Worth checking.....

I have 4 iPhones on my account; 1 5S, 2 5Cs, and 1 4S. All of the 5 series phones are showing the "6-hour" data anomoly. The 4S is not. My 5S shows a lot of data usage in addition to the 6-hour thing and more of a random change in the times of the 6-hour upload. My wife's 5C on the other hand, shows almost nothing outside of the 6-hour uploads and they stay on the same schedule for three days at a time. My son's 5C, is like my usage pattern. Somebody out there (be it Apple or Verizon) knows the answer to this. We're all big boys and girls - tell us why.

I don't think that is the issue (and it is certainly something we already thought of). Of my 3 devices, 2 were backing up to the cloud, one was not. The one that was not was actually the one that was generating the MOST data across this 6 hour cycle.

Okay...here's an update. On 11/22, I went into Settings (on my 5S) and turned the cellular data off. I turned it back on briefly on 11/25 while I was in my car in order to get directions to an unfamiliar location. After 10 minutes or so, I turned the cellular data back off. I checked my usage last night on the Verizon website and, to my surprise, there was only one small data transmission from 11/22 to 11/26 (the short time I had it on in my car). I'm doing all the normal things I do when I'm at home on WiFi but I keep the cellular data switch set to "off". Obviously, I won't follow this pattern all the time. I bought the phone to use, after all, and I intend to take advantage of what it can do but it's nice to know that when my data starts piling up at the end of the month, I can halt the possibility of going over my limit.

Have 3 iPhones in my family and have only had this problem on daughters iPhone 4, with hers it's been every hour on the same minute. I recentley gave her my old iPhone 5 when I got new 5s, was hoping that would solve problem but as soon as she used her iTunes to restore her account to new phone it used data hourly again. I tried deleting all her apps off phone and still did it. Finally did a complete reset and set up as a new phone and that stopped the problem. By using the cloud I was able to get her contacts and pictures on the phone. So I am very sure at least in her case it is some app she put on phone that caused the issue

My family has 4 iPhones: 2 iPhone 5s models and 2 iPhone 5 models. All 4 iPhones are pulling data exactly every six hours, as described in this thread. The 5s iPhones have been using a lot of data at those intervals -- up to 60MB each time -- while the other two, not so much, usually well under 1MB.

Following a suggestion posted elsewhere, I turned off background app refresh (General>Background App Refresh) for a single app, Candy Crush, on one of the two 5s iPhones, making no other changes. Thereafter, the data use continued, but at levels similar to the other two iPhones. The high usage continued unabated on the unaltered iPhone 5s, with about 200MB of mysterious data usage recorded in just over two days. Incidentally, the 2 iPhone 5 phones do not have Candy Crush installed. (My phone is one of those, I hasten to add.)

In our case, at least, it would appear that turning off background app refresh for a single has reduced the problem to a mere annoyance.

I think I have solved the problem for me, but not 100% sure. It was due to my Mail setup. I switched everything FROM "fetch" to "manual". This stopped the "every 6 hours" business. This might also explain why it was happening with my wife's iPhone 5c, but it was happening less (she has less email accounts/calendars and gets less mail).

I will come back and verify that this indeed fixed the "every 6 hours" issue.

Just wanted to add some input here that it doesn't appear to be an iPhone-specific issue. I'm a Verizon customer with 2 5s iPhones and a Samsung Galaxy S4, and all 3 phones are showing the 6 hour interval data usage despite being on WiFi. My usage amounts per phone during these times that it's not worth me finding out (ex. 0.00001 GB), but just to help those who are troubleshooting...it does NOT seem to be an iPhone thing.

I too have this issue with an iphone 5 having ios7. It has been happening for a long time; I am not sure if it also happened before the update from ios6 (my daughter updated the phone). The phone has been replaced by Apple and reloaded from the icloud (Apple suggested this to eliminate possible viriuses that reloading from itunes might allow through); the new phone is doing the same thing. We believe the usage to be from the system services area, specifically messaging or push notifications. What app is causing the cell data usage even though wifi is enabled and connected, is not clear. Our iphone 4's have never shown this issue.

Would it be helpful for people with this issue to compile lists of apps on the various phones to see if there is commonality? I have had Verizon technical support enter a network trouble ticket to investigate further.

There is no issue. It is the way the phone is designed. Every iPhone model and every version of iOS has used cellular data for as long as there have been iPhones. You can confirm this by doing historical searches in the forum. Go back 6 years and you will see posts about it. Push notifications must go over cellular data; it's the way push technology works. Only cellular data CAN "push" - that is, send data to a phone without the phone specifically requesting it. If the phone is connected to WiFi and is on (not asleep) or connected to power after the push notification is received the actual data associated with the notification will go over WiFi; otherwise it will go via cellular data.

You did have this characteristic with iOS 6 and earlier; you may not have noticed it because it is only with iOS 7 that you can actually see how data transmission is allocated to apps.