Reprinted from TidBITS by permission; reuse governed by Creative Commons
license BY-NC-ND 3.0. TidBITS has offered years of thoughtful commentary
on Apple and Internet topics. For free email subscriptions and access to the
entire TidBITS archive, visit http://www.tidbits.com/


   What's Behind Mysterious Cellular Data Usage in iOS 6?

   Glenn Fleishman

   My Twitter feed is full of people telling me about mysterious data
   usage over cellular networks after installing iOS 6 or acquiring an
   iPhone 5. Adam Engst already penned an article explaining potential
   causes and solutions for fast battery draining in iOS 6 (see
   '[1]Solving iOS 6 Battery Drain Problems,' 28 September 2012). This may
   have some bearing on the unexpected cell data consumption, too,
   especially an issue with corrupted Safari bookmarks syncing through
   iCloud.

   But the problem is exacerbated in that many reports I've received are
   from people whose iPhones are set to use Wi-Fi, and they can see are
   connected to a home Wi-Fi network was it's woken from sleep. One
   Twitter buddy, Anthony Hecht, says AT&T [2]told him that when his
   iPhone is in 'idle mode' (standby), it always reverts to cellular,
   which is wrong. Customer service [3]also told him to turn cellular data
   off (Settings > General > Cellular Data) whenever it's idle, which is
   crazy making. He's seen 9 GB in unexpected mobile use, largely while at
   home based on his online charge breakdown, in just a week.

   Many people attributed this program to the Podcasts app from Apple,
   which had already documented bad behavior when downloading and
   streaming over cellular (see '[4]Does Apple's Podcasts App Suck
   Cellular Data?,' 17 September 2012). It can download the same podcast
   file repeatedly. Even after Apple added a switch in the 1.1 Podcasts
   update to restrict data use to Wi-Fi, my colleagues can still track
   cellular downloads with the app, especially if a download or streaming
   was already in progress when walking away from a Wi-Fi connection.

   But several people have also eliminated Podcasts and other podcasting
   apps as culprits. They can see from their online data usage and from
   iOS's tracking of cellular data (or by using [5]DataMan) that the
   device chews through hundreds of megabytes of cell data over short
   periods of time, and they don't know why. Josh Centers is in [6]the
   middle of a vision quest to figure this out, and I expect others are as
   well.

   John Herbert [7]seems to have found one particular bad use case when
   iTunes Match will downlaod over a mobile broadband network even when
   all the switches to use cellular data with Music and iTunes Match are
   flipped to Off. His entry on the topic explains how these settings are
   currently ignored when you start to download items from the cloud or
   have music downloads in queue.

   Over at the Economist's Babbage blog, I suggested that it's [8]hard to
   pin down blame when one can't currently meaure per-app use and thus
   figure out what's going on. But it's completely frustrating. This isn't
   'CellularDataGate,' but it's clearly affecting more than just a handful
   of people, and could involve folks paying dozens to hundreds of dollars
   in excess data usage for what might be an iOS bug or a bug in
   Apple-provided apps.

References

   1. http://tidbits.com/article/13303
   2. https://twitter.com/ahecht/statuses/251719084033589248
   3. https://twitter.com/ahecht/statuses/251726070011789312
   4. http://tidbits.com/article/13266
   5. http://itunes.apple.com/us/app/dataman-real-time-data-usage/id404513413?mt=8
   6. http://joshcenters.com/2012/9/28/followup-on-excessive-iphone-5-data-consumption
   7. http://lamejournal.com/2012/09/24/itunes-match-uses-cellular-data-even-when-you-say-no/
   8. http://www.economist.com/blogs/babbage/2012/09/mobile-data-usage

.