Push notifications explained

Discussion in 'iPhone' started by codz, Nov 24, 2010.

  1. codz, Nov 24, 2010
    Last edited: Nov 24, 2010

    codz macrumors newbie

    Nov 23, 2010
    I did a bit of research about push notification on iPhone and the best explanatory text is here:

    Basically, in regard of a iPhone user which activated the push notifications (one or more apps using it, being the same thing), the Apple's APNS server mantains a "persistent IP connection" with your iPhone in order to deliver notifications when the app (Facebook, email, eBuddy a.s.o) needs to 'say' something to you.

    The notification itself it's a 256bytes of data (at most). But what I wanted to know is how the "persistent IP connection" works and how it's translated in data usage on the iPhone and in battery consumption.

    It is established that push notifications will work either with a data plan (using cellular data) or over WiFi. On other words, your push enabled iPhone will send/receive bits of data frequently with APNS in order to be ready for any push notification. This can be demonstrated by checking the Usage window (in General Settings) from time to time and see the cellular data usage grow some Kbs every 10 minutes or so. If you are on Wifi, this way of data transfer is preffered (in order not to make traffic on user's data plan) and the "persistent IP connection" is done trough Wifi.

    That explains also why the iPhone consumes more battery in an area without WiFi connection if you have Wifi enabled and push enabled - during this permanent connection with APNS the iPhone tries to use Wifi (seeing it enabled) searches for a Wifi network, it does not find it, then goes to use cellular data. All this searching for WiFi network frequently consumes battery.

    That explains also why with push enabled an iPhone consumes more battery on 3G rather than on EDGE/2G (3G disabled) - because every 3G connection uses more battery because it requires connection to at least two carrier towers (as opposes to only the closest tower on EDGE/2G) and that translates to increased power (Watts) from the iPhone.

    Unfortunately disabling 3G is not really an option for iPhone users (especially on iOS 4.x.x) because on EDGE/2G you can't receive calls while a data connection is in progress (you browsing the Internet or push notification keeping that "persistent IP connection" with the APNS - which is also data, or a faulty app like Skype in the background sending data). But that's another explanation (3G/EDGE explained).


    If you want push notification (a very nice functionality) - enable 3G, enable WiFi only(!) where you have a WiFi connection - and be prepared for only one day of normal use of the iPhone, or even less if you are a heavy user of apps that require data transfer on 3G

    If you want two days of using the iPhone (mostly for calls) - disable push notification, set Manual Fetch to your email accounts, enable 3G (in order not to have missed calls because of the EDGE/2G impossible voice over data)

    If you want three days of using the iPhone - disable push notifications, set Manual Fetch to your email accounts, disable 3G (but be sure there is no app in the background using data connection), and set Airplane mode during the night (understanding you will not be able to receive any calls during that)

    Note: The above are for the iPhone 3GS, as for iPhone 4, having a 1420mAh battery vs 3GS's 1219mAh, it should last two days with push and three days without push.
  2. SomeDudeAsking macrumors 65816

    Nov 23, 2010
    Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_2_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8C148 Safari/6533.18.5)

    For most things, push notifications are as annoying as he'll. I don't want my phone going off every minute because some game or someone just updated their FarceBook page.
  3. gtmac macrumors 6502a

    Jun 25, 2010
    Agree 100%
  4. kosmiq macrumors newbie

    Sep 6, 2010
    I think Push notifications are great and I use then. Moreover I always have WiFi enabled and I also have 3G on at all times. I also consider myself a normal user who surfs, checks facebook etc on my phone and my battery often lasts two days without problem. I am however very often on a WiFi network both at work and at home.

    iPhone 4 here in Sweden.
  5. codz thread starter macrumors newbie

    Nov 23, 2010
    Having Wifi at work is best, that way the phone will use Wifi though 3G is enabled (Wifi has priority) and battery life is max
  6. Daveoc64 macrumors 601

    Jan 16, 2008
    Bristol, UK
    Normally dragging up an antique thread like this is annoying, yet this provides an opportunity to correct both of your posts!

    When an iPhone is not connected to mains power, it will only use Wi-Fi:

    1) When the screen is "on" (not in sleep mode)
    2) When an application is using the Wi-Fi connection (e.g. Pandora)
    3) When Cellular data is unavailable
  7. Travisimo macrumors 6502a

    Dec 22, 2009
    I really like push notifications and don't mind the battery hit. However, some of them just aren't consistent, like the Facebook app. More than half of the time, I don't get a push from Facebook. It's not consistent at all, so I have to rely on push e-mail notifications instead for that.
  8. TheNewDude macrumors 6502a

    Mar 17, 2010
    Totally agree! Facebook has the WORST push notification ever!! I am not a frequent facebook user but get messages on it from time to time. Sometimes I don't find out I have a message till 3-4 days later when i manually check for them.
  9. codz thread starter macrumors newbie

    Nov 23, 2010
    Dave, seems you're right, Wifi is off on screen lock, and 3G/G is used for push notification (persistent IP connection). That explains adding "cellular data on/off" in iOS 4. With that off and in a Wifi area all is great.

    Why then the official recommendation to turn Wifi off when you're not in a Wifi area? While the phone is locked Wifi is not searching for hotspots. Anyway 3G consumes more than Wifi so why turn off Wifi is ahead turn off 3G in the official recommendation for battery life
  10. frankge973 macrumors newbie

    Dec 19, 2012
    I've iPhone4 with Ios 5.1.1.
    Why I receive push notifications delayed ? (6/7 minutes)?
    I've seen that this doesn't happen when iPhone is over Wifi or when it is connected to supply.
    And I could say also that previously didn't happen with anothe mobile operator.
    In which way I could solve this severe problem?
    My mobile operator says that for them all it's ok.

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