The iPhone 5 uses Cellular Data over WiFi?

I ain't arguing with you. Just go read 45 pages of complaints in this thread.

You may be obsessive, but it is NOT happening with anyone that I know, including myself. It may be a bug on your phone but it is not happending to mine on AT&T. And how many of the 45 pages of people here (totalling maybe 100 people) are using an unlocked iPhone on T-Mobile USA?

I'm on EE in the UK. I also know of this happening on the O2 network (UK again).

Bugs are strange things. They don't happen all the time or on all installations of the same software. I know this from bitter, professional experience ;-)

Ian.

Not bitter from any of my experience, but intermittent bugs are always the worst to try and suss out and take the most time. And when you have so many user variables involved (iPhone model, carrier, WiFi system) it is even harder to narrow down.

Are you working with Apple support on this? Sent in detailed feedback? If you disable cell data and monitor your router are you still sending out 450k data per hour?

Yes, I spent half an hour on the phone with Apple Support. They didn't know what the **** was going on and they referred me to the feedback site. I left detailed feedback.

One has to admit, the Apple knowledge base article about cellular being used in preference to Wi-fi smells a bit fishy to me...

Ian

Which knowledge base article says that? The only time that is true is when the phone is not connected to power and goes into sleep mode. At all other times WiFi takes preference over cell data. There was an initial problem with the Verizon iPhone 5 but that was fixed through a carrier update. With mail there is one other situation where cell data can take precedence, i.e. if the WiFi connection has encountered a problem in sending/receiving mail it will flip over to the cell data connection.

http://support.apple.com/kb/TS4264

Ian

That is only for APN's, which are very small and is the exception to the rule.

But, anyway, that KB article must be wrong or out-of-date. I've managed to rack up an hour's phone usage, with plenty of APNs received, with zero cellular usage.

I guess my point is that apps (or services) are clearly capable of being able to deliberately prefer cellular to Wi-fi and I'll bet that (due to a combination of factors, as you rightly point out) the Exchange ActiveSync persistent connection is incorrectly preferring cellular data on some devices.

Ian

maybe its time to look at a side issue: dump proprietary ms exchange and use open standards like caldav, carddav and imap. if your IT is not impressed, tell them to update themselves to reality.

I doubt that, it would have no way to do so. But what can be happening (especially with an Exchange/ActivSync account) is there can be a password issue between the iPhone and the Exchange Server. This will cause the iPhone to constantly poll the server (which can be seen by the Exchange administrator). If during this polling the iPhone is disconnected due to going to sleep mode, or you move away from the WiFi hotspot, it will use cell data to poll the server.

Which type of APN's did you receive in an hour and how many of them. This would not could pushed emails, text messages, or iMessages.

You are right that this is an application specific problem, and that's why it's hard to test. I found it was an interaction effect when particular apps are running at the same time, and they are both wanting bandwidth, one ( in my case nfl rewind) would switch to cellular.

I can assure you it's happening. My wife and I both have iPhone 5 on AT&T, not jailbroken. She upgraded to iOS 6; I did not. As soon as she switched to iOS 6, she started having large cellular downloads in the middle of the night, when there is wi-fi available. She overran her data plan in a matter of days, whereas she had never come close to 50% usage with iOS 5.

We managed to get it under control by a) getting her a larger data package (at extra cost) and b) disconnecting all the email and iCloud services. It still consumes more cellular data than it should when there's Wi-Fi (I use my iphone 3x as much as she does, and don't have anywhere near the cellular data usage she does), but it's manageable and we've stopped the overages.

This is definitely a bug in iOS 6. Why it doesn't happen all the time and you and your friends are lucky duckies, I have no idea, but I'm not a lazy Apple engineer making the big bucks either. What I do know is their sloppy programming is costing me money I didn't expect it to. These are probably the last iPhones we'll buy since Apple shows no interest in fixing the problem. These 45 pages have gone unanswered for many months now.

My testing to determine cellukar data leakage was done with the phone charging and non-idle and streaming a video over Wi-fi (AirVideo, which doesn't work over 3G).

The APNs I received during the zero-result tests were a few for Facebook, a few from Gmail and an iMessage. In the space of an hour or so. Zero cellular data usage (with push email disabled).

Oh, I've also tried disabling the Wi-fi and seeing how much background cellular data is used with all notifications disabled, push email enabled and, amazingly, it's also around 450k per hour.

If it were an issue relating to Wi-fi occasionally dropping out and reverting briefly to cellular, I would expect to see significantly less cellular data leakage but it was almost exactly the same.

Ian

If it was a "bug" as you say, it would also be happening on my iPhone 5 on AT&T and I'm not seeing it at all.

Are these large downloads (how large) showing up on her phone cell data usage or on the bill?

Have you tried leaving her iPhone connected to power at night and see if it affects the cell usage?

Does she have an Exchange account on her iPhone.

Have you sent detailed feedback information?

How do you know Apple shows no interest in fixing the problem?