1 2 Previous Next 27 Replies Latest reply: Jan 7, 2011 6:17 AM by David Barash
Mark Hollingsworth Level 1 Level 1 (10 points)
What is accurate?

My usage under general says some 100 Meg more than when I check my data usage in my account on AT&T.

Anyone else notice a large difference? What is accurate?

Mac Pro- 2x2.26 Quad-Core, Mac OS X (10.6.3), 6 gig RAM- 30" monitor
  • 1. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    David M Brewer Level 6 Level 6 (9,200 points)
    Go with the AT&T usage. That the account (usage) that will charge you if you go over your allotted usage.
  • 2. Re: Data usage. IPad shows a lot more than the info on my account at AT&T
    araym Level 1 Level 1 (5 points)
    My usage is way off too, but in the opposite direction.

    The last time I was able to check AT&T reported that I had used 140 MB this month so far. (This is my first month by the way.) However my iPad under Settings->General->Usage->Cellular Data Network reports I have sent 12.2 MB and received 74.4 MB for a total of 86.6 MB. That's quite a discrepancy. And no, I have not reset these counters, ever.

    You'd think they would be the same. Is anyone else seeing large differences? Can anyone explain this?
  • 3. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    Mark Hollingsworth Level 1 Level 1 (10 points)
    I was thinking perhaps the AT&T sie was just slow to update.
    But of course you pay off the AT&T info. I had just used it a lot over a day and wanted to keep track.
    I wonder if the iPad got mixed up when getting data from wifi and 3G.

    Mark
  • 4. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    lllaass Level 10 Level 10 (142,130 points)
    There have been past posts on this issue. No one knows why (AT&T was contacted) there is a difference. Usually the iPad shows lower usage.
  • 5. Re: Data usage. IPad shows a lot more than the info on my account at AT&T
    Bill Aviles Level 2 Level 2 (215 points)
    I didn't want to boot up my iPad to check, but I know that there are two places where you can check your usage. The one under "General", IIRC, is one that you can reset to zero. If you've never reset it, it's showing you your usage since your iPad was first activated.
  • 6. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    Charles Minow Level 6 Level 6 (9,190 points)
    araym wrote:
    You'd think they would be the same. Is anyone else seeing large differences? Can anyone explain this?


    I don't see a large difference, but one way to explain it is that AT&T bills by the megabyte, and the iPad is just reporting any usage, no matter how small. So you could download a 20k picture and the iPad counter would say it's downloaded just the 20k. But, depending on how AT&T is counting, you could get charged 1 megabyte by them.

    charlie
  • 7. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    araym Level 1 Level 1 (5 points)
    So you could download a 20k picture and the iPad counter would say it's downloaded just the 20k. But, depending on how AT&T is counting, you could get charged 1 megabyte by them.


    Perhaps but you would expect to see at most 1 MB difference due to this rounding effect. But in fact I've seen up to a 53 MB difference.

    AT&T might round up to the next integral MB, but they're not going to really charge an entire MB every time you request 20 KB, then charge another full MB for a second 20 KB request.
  • 8. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    Charles Minow Level 6 Level 6 (9,190 points)
    araym wrote:
    AT&T might round up to the next integral MB, but they're not going to really charge an entire MB every time you request 20 KB, then charge another full MB for a second 20 KB request.


    Think of this scenario:

    You connect to the AT&T network, download 20k and then the iPad disconnects from AT&T. AT&T charges you for 1 MB. Then, a few minutes later your iPad connects again, downloads 20k again, and disconnects. The iPad will show 40k of usage total, but AT&T will show 2 MB. Repeat this process even a couple of times an hour, and you can see how there could be a big discrepancy.

    Is this what's really happening? I'm not sure, but it seems like a reasonable explanation.

    charlie
  • 9. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    araym Level 1 Level 1 (5 points)
    Is this what's really happening? I'm not sure, but it seems like a reasonable explanation.


    I respectfully disagree - that is not reasonable at all. AT&T has to keep statistics with more granularity than that. Otherwise in the case you cited they are overcharging us 50x. That would be fraud and they'd soon have a class action lawsuit on their hands. Even if the numbers are different (I know you made them up to make a point) they would still be guilty of overcharging and exposing liability on their part.

    I'm willing to accept that they are rounding either up or to the nearest full MB ... for reporting purposes. I'm not willing to accept that they are charging for a full MB everytime a few bytes get pulled down. Otherwise you'd only have essentially 250 "sessions" per month, not 250 megabytes per month.

    <Edited by Host>
  • 10. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    Charles Minow Level 6 Level 6 (9,190 points)
    araym wrote:
    Is this what's really happening? I'm not sure, but it seems like a reasonable explanation.


    I respectfully disagree - that is not reasonable at all.


    I meant resonable as in logical, not reasonable as in I'd be happy with it if it was the explanation and I was seeing the discrepancy.

    AT&T has to keep statistics with more granularity than that.


    Look around on AT&T's website to find the data agreement. It clearly says they bill in full megabyte increments. They may or may not keep track with more granularity than that, but it's irrelevant for AT&T's billing purposes.

    I would stongly suggest you contact AT&T to find out more about how they track usage.

    I'm willing to accept that they are rounding either up or to the nearest full MB ... for reporting purposes. I'm not willing to accept that they are charging for a full MB everytime a few bytes get pulled down. Otherwise you'd only have essentially 250 "sessions" per month, not 250 megabytes per month.


    That sounds to me exactly like an app that's getting some notification periodically. Maybe that's why I don't see this discrepancy: I keep notifications turned off most of the time (though somehow Mail still knows I have email).

    charlie
  • 11. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    araym Level 1 Level 1 (5 points)
    Charlie,

    I about fell out of my chair when I read your note saying that AT&T rounds up to the next highest MB. However I was so flabbergasted that I went onto their web site and I think you're mistaken. I downloaded the user agreement and it states:

    2.6 How does AT&T Calculate Data Usage?
    DATA TRANSPORT IS CALCULATED IN FULL‐KILOBYTE INCREMENTS, AND ACTUAL TRANSPORT IS ROUNDED UP TO THE NEXT FULL‐KILOBYTE INCREMENT. AT&T CALCULATES A FULL KILOBYTE OF DATA TRANSPORT FOR EVERY FRACTION OF THE LAST KILOBYTE OF DATA TRANSPORT USED ON EACH DATA SESSION. THE FULL KBs CALCULATED FOR EACH DATA SESSION AS WELL AS THE KBS YOU ARE USING ARE TOTALED DURING THE BILLING PERIOD UNTIL YOU REACH YOUR ALLOTED MBs or GBs, AT WHICH POINT YOUR ACCESS TO DATA SERVICES WILL CEASE. DATA SENT AND RECEIVED INCLUDES, BUT IS NOT LIMITED TO DOWNLOADS, EMAIL, OVERHEAD AND SOFTWARE UPDATE CHECKS.

    So it appears they're charging in full KB increments, not MB increments.

    That might still explain why the iPad counters are lower than the AT&T counters, if the iPad accurately counted each byte without the snap up to the next KB boundary AT&T is using. However I'm still surprised at how far off my own counters are.

    I guess it now remains to be seen how AT&T defines "session" above. Does it mean a login sequence start to finish? Does it mean each logical transaction between a user and a single site (e.g. a single email or a single web page presentation)? Does it mean a single request for service, e.g. each separate component within a web page? Or does it mean each full TCP session? Depending on how they define "session" (and I note that it is undefined in their user agreement) they could be pretty far off of the iPad counters. Indeed I think that is the real cause...

    So this was an interesting discourse. To finish it off however I suspect we're going to need inside help from AT&T since they didn't see fit to define "session" for us, and hence we're left to only speculate...

    Ray
  • 12. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    Charles Minow Level 6 Level 6 (9,190 points)
    araym wrote:
    I about fell out of my chair when I read your note saying that AT&T rounds up to the next highest MB. However I was so flabbergasted that I went onto their web site and I think you're mistaken.


    Yeah, you're right. I was reading the wrong user agreement: there's another that talks about billing that says that some plans are billed by the KB and some by the MB. Since the AT&T counter only shows MBs, I made a leap and thought that they were billing by the MB.

    charlie
  • 13. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    Michael Morgan1 Level 7 Level 7 (23,825 points)
    I had the same or, rather, the opposite problem — Usage in Settings well below that being reported by AT&T — and was coming in here to see if anyone else was seeing this.

    In my case, I upgraded to the 2GB plan a bit less than three wks ago, when it became clear that I'd be out of wifi for a while and when the type of use I had in mind would have quickly burned through my existing 'basic' data plan.

    I reset the counter in Settings at the same time as I upgraded and thought that it was tracking along reasonably and consistently with what I was doing, which did include a week in the middle with routine wifi access and with cellular mostly turned off.

    Anyway, was showing a bit over 1 gig downloaded and considerably less than that uploaded and was happy with that right up to the point where the screen message popped up with its 20% warning and the associated email.

    AT&T seems convinced that I'v used about 600KB more than my iPad shows and, frankly, I tend to think that my numbers are closer than theirs. I've been quite light on streaming stuff, watched no movies, very little time on Pandora or anything like that, etc.

    This discrepancy is too big to lay off to rounding errors but I clearly can't know for sure, right now, which of the two figures is the more accurate. My short-term solution, given that I'm coming back off travel for a while and won't need it, is to simply cancel the data plans and run only wifi. I was in the habit of keeping daily track of data usage anyway, but in the future I will also be comparing the figures displayed there with what's being presented in the accounts area. I also will be contacting AT&T to see if I can get a better handle on this.
  • 14. Re: Data usage. IPad shows a lot more than the info on my account at AT&#38
    araym Level 1 Level 1 (5 points)
    I had the same or, rather, the opposite problem — Usage in Settings well below that being reported by AT&T


    That’s exactly the same problem the rest of us are having. It’s becoming pretty clear that the iPad is counting the exact number of bytes sent & received whereas AT&T in their user agreement says they “round up to the next full-kilobyte increment … on each data session”.

    This reminds me of the time several years back when the public learned that the carriers were rounding up to the next higher minute when you placed a voice call, e.g. if your call lasted 9 minutes and 1 second you got billed for a 10 minute call. The difference here is that voice calls are well defined; it’s clear when they start and when they end. However on a computer, “data sessions” can mean many different things. Indeed I find it very ironic that in the AT&T document entitled “Session Based Wireless Data Services Agreement” the word “session” is completely undefined!

    A single web page load could be interpreted as a session for example. But given how bad the discrepancy is for some I think it is pretty clear that AT&T defines a session with much finer granularity, thus giving them more opportunities to “round up”. Each little graphic, each frame, each ad, each component or object within the web page, etc. are all likely to be “sessions” with each one rounded up to the next full KB increment. In the worst case scenario, a simple TCP ACK which is only a few bytes long could be counted as 1 KB. Who knows?

    The problem is likely to be exacerbated by having many shorter web interactions rather than fewer longer ones, since each separate interaction provides for greater opportunities for AT&T to “round up” “sessions”. That in turn explains why some people are off by a few hundred KB only while others (like me) are off by several tens of MBs. The nature and usages by each customer is going to be different.

    Only AT&T knows for sure what a “session” means to them. They need to define their terms so that their users are aware of the true agreement for which they’re signing up.

    Ray
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