IPhones do use cellular data while on wifi, but not much.

Discussion in 'iPhone' started by wvphysics, Jul 14, 2010.

  1. macrumors regular

    Jul 7, 2010
    With the number of threads on here of people complaining that their phones are magically sucking up large amounts of data, I thought there should be some clarification. The large amounts of data registering on bills at ~2 am is simply the system tallying the usage from the last tally. That said, I have noticed that based on the phones usage meter, mine and my wife's phone uses a little cellular data while connected to wifi. At first I thought it was only while in "sleep" mode. Icould reset statistics put it in sleep for a minute then I would wake it up and see "3G" at the top and it would quickly switch to wifi and I could see say 10kb sent and 4kb received. Later, I could see it going up without putting into sleep so not sure. It stops if I turn off cellular data. MY wifes phone does it too, but shes been staying around 1MB to 1.5MB a day, so I cant see this data usage to being more than 1 MB a day.
    Now, this only raises the quesion of what is going on here, as I still don't know if the data my phone is registering is even registering with ATT. I called ATT and surprise, they had no clue and claimed ot have never heard of it. They even sent me to their "techncal apple department".
    Anyone have ideas or other related observations? Please, no "OMGZ I never used more than 100MB a month and suddenly I use 200 in a week" posts unless you have thoroughly looked into it. Most of those posts have turned out to be a new app like audio or video streaming.
  2. macrumors 68040


    Feb 5, 2009
    Some services are 3G/E only, such as location services, ect.
  3. macrumors 68000


    Jan 6, 2009
    Washington, DC
    My 3gs with no SIM in it uses location services just fine with WiFi on.

    To the OP, I can't really answer your question, but there isn't anything my 3gs can't do without a SIM in it that it did with a SIM in it regarding the internet.
  4. thread starter macrumors regular

    Jul 7, 2010
    Define location services, I can have nothing in multitasking and it occurs. So no navigation software or photo services up etc.
  5. macrumors 6502

    Jun 23, 2010
    Now, there well may have been something wonky with my iPhone 3g, but I can tell you pretty definitively, that my phone used lots of 3G data while it should have bene on WiFi. I repeatedly would reset my data usage only to see it go up and up while on WiFi. Probably 10 or more meg each day.

    Now, with the iPhone 4, My data usage has tumbled. I was between 350-536 meg a month for an average of 433 meg and so far in the first 11 days of my billing period, a time which works out nicely with my with my purchase of the iPhone 4 on launch day so that only iPhone 4 usage is in the billing period, I have used 38 meg so far. On track to be 1/3 of my lowest usage and 1/4 of my average according to the ATT tracking site, even though I have if anything, used the phone more than before due to it being new. Certainly no less.
  6. thread starter macrumors regular

    Jul 7, 2010
    I have seen a few people report corrupted apps causing large data usage, but I don't think they specified that it would use 3G while on wifi. I imagine AT&T wouldn't give a refund for a corrupted app either, much like the power company won't give a refund for a shorted out heater overusing electric ( had that happen actually).
  7. thread starter macrumors regular

    Jul 7, 2010
    I use over a gig a month, but I also stream audio for a few hours a day at work.
  8. macrumors G5


    Aug 1, 2004
    St. Louis, MO
    Visual Voicemail goes over the cellular data connection, regardless if WiFi is on or off. Keep that in mind.
  9. macrumors 6502

    Jun 23, 2010
    Part of the problem I saw was that the phone would drop the WiFi connection every time it went into sleep mode and would only use 3G, only resuming WiFi when the phone screen was unlocked again.

    My iPhone 4 keeps the WiFi going at all times and will have maybe a couple hundred kb usage all day if I stay in range of Wifi.

    The only question I have, was did all iPhones do this prior to iOS 4 or the iPhone 4 or was mine acting strangely and using data.

    I could totally see them making it behave like this in an attempt to save battery and then changing it when ATT decided to start doing metered data.
  10. macrumors 6502a


    Oct 26, 2007
    So if you turn off cellular data, does that disable visual voicemail ?
  11. thread starter macrumors regular

    Jul 7, 2010
    Good to know, but I will say I wasn't using visual voicemail whn I saw the data going up. Seemed more often to do it when I woke from sleep and briefly saw the 3G symbol.
  12. thread starter macrumors regular

    Jul 7, 2010
    Looking over my bill, days I'm at work I use alot (audio streaming and such) weekends I seems to use around 1 to 2 MBs which is around what my wife uses and she doesn't go out much most days. So I'd say what ever its doing both those iPhones are using around 1MB of cellular data a day whether on wifi or not.
  13. macrumors 65816


    Feb 29, 2008
    Los Angeles
  14. thread starter macrumors regular

    Jul 7, 2010
    I rarely get voicemails. So I check a voicemail maybe twice a month.
  15. macrumors newbie

    Jun 30, 2010

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