Q: Unknown Data Usage on IOS 6

Have you started using any new apps that may be data heavy?

Are you using iTunes match, or automatically downloading purchases on cellular?

See settings-iTunes & App Stores, automatic downloads/use cellular data, ensure they are off.

See music-iTunes Match and ensure use cellular data is off

Also are you using facetime over cellular?  If so that may be a huge use of your data plan.

One last thought, ensure your "personal hotspot" is off.  Just to be sure check settings-personal hotspot and ensure it is off.

I haven't noticed any uptick in data usage.  I have verizon as well. 

It certainly isn't any bug I've heard of with iOS 6.  See Apple - Feedback

I'm having the same problem, only I have a 200MB plan, so I'm burning through increments every three days. I've heard the problem may be Podcasts, which makes sense to me (it's the app I use most often), but I had set it NOT to use cellular data. BTW, I'm on AT&T, not Verizon, so it doesn't seem to be a problem specific to any one carrier.

It's a real, serious issue. Make sure you speak to your carrier and Apple and get notes put on your account to get out of any excess charges:

http://forums.whirlpool.net.au/archive/1985068

I'm having the same issue. My habits since upgrading to iOS 6 have not changed, I'm connected to WiFi basically all day. My average data usage since owning an iPhone (4+ years) is 1.3 GB a month. I've burned through data at a rate of about 850MB a day since upgrading. I can't figure it out! I've adjusted all of my settings to not use cellular (iTunes Match, syncing, etc.) and have been closing all apps after use, again, per AT&T's recommendation. This is insane. The way this is going, my bill this month is going to incur about $400 in overage charges. What can one do?!

I spent half an hour on the phone with an Apple rep yesterday, trying to diagnose the problem. We reached no conclusions, but I noticed:

• Usage seems to have to have returned to normal after rebooting the phone with all apps closed (done the evening of 9/27); and
• AT&T gave me high usage spikes on 9/24 through 9/27, with the pattern of just one big lump billed between 9 pm and 9:40 pm, whereas the usual pattern is a few small blips of usage throughout the day.

So I'm guessing that there is a bug in the Podcast app that resulted in continuous communication throughout the day via cellular data (even though I have cellular data turned off for Podcasts, even after closing the Podcast app) and that it was interrupted by the reboot. AT&T was willing to give me a credit on my bill, so definitely report it to your carrier, too.

It's a bug.. Found out that ios 6 beta had this feature called cellular over wifi. It uses cellular data sometimes even if u r on wifi. It is supposed to be removed from the final version that we are using now. I found out when I tested my 3G speed using speedtest app and it was showing me download at 30mbps when the theoretical limit for 3G is only 7.2 .. I have a screenshot to prove it. Showed it to my colleagues and they were surprised as well. Apple needs to fix this.

If none of you tell apple they will never know. See http://www.apple.com/feedback/

I have had an iPhone on AT&T since launch. I never went over a gig in any month. I have used half a gig in 2 days with Verizon!! Worse, it uses LTE while I am at home with a rock solid wifi connection. If I turn cellular off altogether I can still see, for example, a YouTube video. But if I leave it on, while still connected with wifi, it ***** data like a vampire. I don't stream video, use Itunes match, pandora, etc.

A single view of a regular web page--say, NY Times, will register as 15mb!!!

And, all day, it leaks data even with no apps running!

I spent over 4 hours on the phone with Verizon.  I called today to check the status of this problem, and found that they had not even opened a ticket!!

They have assured me that I will not be charged for any overages, but this is a huge problem.  My wife's ATT Iphone 5 has used maybe 100 mb in the same period, which would be completely consistent with our usage.

So far, nobody at Verizon has said a peep, but this is all over the place:

http://forums.macrumors.com/showthread.php?t=1456838

http://tidbits.com/article/13304

http://forums.macrumors.com/showthread.php?t=1454883&page=3

https://discussions.apple.com/thread/4373365?tstart=0