iPhone 4 using Cellular Data when on standby and connected to wifi.

Does your wi-fi router work with other devices? Especially mobile devices? If they don't connect or take a long, long time to do so, there might be something wrong with your router.

Oh yeah, and by the way, there is a way to turn off cellular data, yet keep wifi on. Just turn on airplane mode (settings, it's right there), and afterwards, turn on wifi. There you go!

You can shut of 3g/celluar usage in settings -> general->network -> cellular. the second setting on that screen shuts off all cell data transmission. I leave it off all the time unless I need it, since I don't have a high data plan.

https://discussions.apple.com/thread/3855412?answerId=18055498022#18055498022

Here is my question that is in a similar vein and the answers tend to be the same. I am have simply gotten into the habit to turn cellular data off at home and on when away from home.

It would seem that the power savings outweigh the cost for increased cellular data consumption.

Thanks, I understand now that I just need the turn-cellular-data-off habit. Just wish I didn't have to count on my brain to remember to do that. 😐. Thank you!

I've been experiencing a similar wi-fi "time-out" issue with my iPhone 4s GSM (iOS 5.1). This occurs when I'm listening to radio streaming with the phone in sleep mode and using battery power. It happens like this: With wi-fi active and indicating full relative strength (3 bars), I open a streaming radio app such as TuneIn Radio Pro or ooTunes, select a station, set the volume and upon hearing audio, hit the power button to enable sleep / screen-lock. After about 20 - 30 mins, the audio will abruptly stop. Upon manually waking the device (via the power button) I'm greeted by a screen dialog stating (correctly) that my app settings do not permit radio streaming via cellular data. The wi-fi "bars" are curiously absent with my provider's cellular "3G" identifier displayed instead. Within 10 to 15 seconds the "3G" reverts back to the expected wi-fi bars and after I dismiss the dialog, the streaming audio returns. By the way, I also listen to streaming with the exact same apps on my trusty old first-gen iPod Touch (iOS 3.1) via the same wi-fi router with no such disruption. In fact, the only limiting factor here is the battery (charge) level, which after a fresh charging session usually holds out for the better part of 4 hours of listening. My conclusion: The present implementation of the 4s and iOS 5.1 does not support a persistent wi-fi data transfer duration - at least while the device is in the sleep/lock mode. At some point, the phone disables the wi-fi and any app(s) that had been using wi-fi data will now attempt to use cellular data - should it's settings allow it to do so. Fortunately in my case (my cellular plan allows for only a very modest data transfer limit), the app settings intervened and prevented this from happening.

I too am experiencing mysterious cell data use. I am on the Bell network in Canada. I leave the iPhone 4s plugged in at night *and* I have the cell data setting switched to off. Yet, I often use a lot of cell data overnight, sometime between midnight and 6am. The other night I used 16mb of cell data. There are no apps running at all.

I checked Bell's online data use system and all the data appears in my unlimited social networking section, rather than the 500mb of regular limited cell data use.

The only social networking app that I had installed on my iPhone was the official twitter app. And the increased data use seems to have coincided with adding more people to follow on twitter and making a bunch of lists on twitter.

I uninstalled the official twitter app, and last night there was no cell data use overnight.

Again, I have the use cell data setting off. So it seems that something, perhaps the official twitter app, is bypassing the turn off cell data setting, and is using cell data anyway.

Has anyone else observed this?

Thanks...

Have you tried writing down (or taking a screen shot) the Usage screen before you go to bed, and again in the morning, to verify that the usage was overnight, and not usage from earlier in the day that was merely posted to the billing system overnight? Or used an app like DataMan to see exactly how much data was used by what app at what time?

I have seen this cell data use pattern using ondevice data apps like the Wali Data Usage Defender and in Settings --> General --> Usage --> Cellulsr Usage, long before checking online with my provider. Perhaps I should have been clearer on that point in my first post.

I had noticed a a MB or 2MB sometimes overnight, even with Cellular Data set to off, and was never that bothered by it and didn't bother to go online to my provider's data use monitor to look into it in more detail. I had been using Twitter, but honestly had only subscribed to literally one or two feeds. Then a few days ago, after taking the plunge to subscribe to more feeds and organize them by lists, was when I noticed the large overnight cell data use in the Wali Data Usage Defender app, v1.7.2, and decided to log into Bell Mobility's website to see more data use details under my account and saw that the 16mb data was all under the unlimited social networking meter, rather than the 500mb monthly limit meter. Therefore I've concluded it must be the official Twitter app doing it as that's the only social media app I have installed.

Yesterday, I uninstalled the twitter app, installed DataMan, the full version of the app, and neither it nor the the Wali app detected any cell data use overnight that circumvented the all cellular data off switch in the phone's settings.

If it is all social media data, and I have an unlimited plan for that, I don't really mind. But it makes it hard to track my data use. Plus, if I have all cellular data turned off, I would expect just that. I wouldn't expect an app to circumvent that setting somehow.

Thanks...