If you’re on one of AT&T’s limited data plans, you’d better start carefully monitoring the data usage, because some customers are noticing unexplainable daily hits on their accounts. The support forums at Apple are filled with pages of theories and complaints from frustrated customers, but our tipster David got the following admission directly from an AT&T rep: “She told me that most, if not all, 3g-capable iPhones were being charged erroneously like I had been experiencing. She told me AT&T was unaware of why the data was being charged, and where it was coming from.”

The transmissions usually occur in the early morning hours, and although there are lots of theories floating around, none fully explains what’s going on.

On my own most recent bill, there’s a daily transmission every morning between 1 and 5 a.m. (when I’m usually asleep), for a total of 23.5 MB of unaccounted for data against my monthly limit. Because I carefully restrict my 3G data consumption, this hasn’t proven an issue for me yet. But that’s not the case for everyone: David says he was hit with a single transmission of over 50MB one morning that put him over his monthly limit, which meant he had to pay AT&T more money for data he never used. Neither he nor AT&T can explain what was transmitted to account for that high number.

If you read his full post you’ll see that AT&T has no idea what’s going on. The initial CSR lied to him, the second one talked down to him, and then he was ignored completely until he shamed AT&T earlier this week via Twitter. That’s when someone at AT&T contacted him directly. Unfortunately, this still didn’t fix the problem:

…Much to my surprise, I received another call from AT&T, this time from someone much higher up in AT&T. The woman informed me that I had brought erroneous data charges to the attention of AT&T. She told me that most, if not all, 3g-capable iPhones were being charged erroneously like I had been experiencing. She told me AT&T was unaware of why the data was being charged, and where it was coming from, but that the issue would be fixed shortly and that all the erroneous charges would be removed. I was shocked that AT&T would finally admit to a problem this large, especially considering that chunks of incorrectly-charged data could quickly eat-up the relatively skimpy data plans that AT&T now offers.

[…]

ADDENDUM: (9/1/10)

I was able to check my data billed this morning, nothing had been removed and instead I was billed for another large chuck of data. This is really starting to cause a headache for me because now I have used up half of my allotted data for the month, with 25 days left, and I have to keep track of what I know I didn’t use so I can dispute it later.

If you want to keep track of your real data usage so that you can compare it with what AT&T says you’ve used, you can reset your iPhone’s built-in usage counter when your billing period resets each month. On your iPhone, go to Settings > General > Usage > Reset Statistics. (Don’t confuse this with the reset button in the “General” pane.)

Note: cat usage is demonstrated with original Edge-only iPhone, so it cannot explain 3G data usage.

“Topic : Unknown data usage early morning” [Apple Support Forums]
“AT&T Admits to iPhone Data Calculation Errors” [Stupid Hipster Doofus]

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