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What is system services using push notifications for?

H

humpbacktwale

macrumors regular
Original poster
Dec 20, 2019
204
33
The only two apps I have mobile data allowed for are Whatsapp and Signal. Now I am assuming that any data usage for them will be registered under them in mobile data. However, yesterday I reset my statistics and checked after an hour, and push notifications uses twice as much as either of them combined. I don't have anyother notifications enabled, and no other apps were open or have any logged data usage. Does this mean that, even though the data usage is related to those two apps, it gets logged under system services because incoming messages are related to notifications? This is the only explanation I could think of.
 
Notifications and mobile data are different things. Any app that puts up a notification uses Apple's push notification service to communicate that notification. That's how you get the badge on Mail, for example.
 
Ok so the mobile data usage of the app itself is separate from anything to do with notifications from the app, or I also assume the checking for notifications, for any time the data increases and there hasn't been any new ones?
 
This is correct. In fact, I had disabled iCloud entirely at this point. If you only log into your apple account via the app store, icloud is turned off unless you specifically go in to set it up.
 
Can see that sort of usage, as Apple Push Notification Services (APNS) is more than just an alert mechanism. It can push other data in the "message" as well.

So, made up example, a "hello" alert might have "hello", name of sound to play, name off sender, data to feed to the app itself, possibly action buttons.

Basically, a five character in-bound message/alert will use more than five bytes of data. And an outbound, might very well be significantly less as just sending a message and recipient info without extra baggage that the APNS data packet contains. Add in if getting pinged a lot and not responding to all alerts, will skew toward more on alerts vs outbound wrt data usage.

ADD: Example, three person chat. A initiates, B & C reply, B replies to C, C replies to B, A finally replies. Four alerts generated by B & C before A actually sends any new data back out. If alerts are "heavy" and A replies with simple "k" like message, just chewed through a fair amount of data just on alerts.
 
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To confirm, even for a messaging app like Signal, the mobile data usage of the app itself can be less than the mobile data usage as a result of the push notifications assocaited with the messages for the app, and that the data usage of push notifications can rise even if there have been no notifications?
 
It should not rise if no Notifications. But otherwise, yes. Apple push Notifications can be up to 5012 bytes. So as mentioned, a "k" reply might actually have a lot of other things going along for the ride in the Notification.

Example from Apple's developer documentation, a simple Notification:

Code: 
{
   "aps" : {
      "alert" : {
         "title" : "Game Request",
         "subtitle" : "Five Card Draw"
         "body" : "Bob wants to play poker",
      },
      "category" : "GAME_INVITATION"
   },
   "gameID" : "12345678"
}
 
The notifications themselves might be only 5kb, but the amount that it rises given the amount of notifications I would get simply doesn't match. I'd get it goin up by 100-200kb with only a few notifications. It definitely consumes data outside of just actually sending notifications.

For example. currently its on 1.8 MB after 20 days, but that would require 360 notifications on mobile, which I don't think has happened. Its also definitely went up after I've reset the statistics, and receieved no notifications.
 
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From my understanding of APNS, you might be getting "stealth" Notifications.

For example, if you have a social media app installed and said "OK" to allow push notifications, turning off Notifications on the device does not stop getting Notifications. APNS will push Notifications, and then the device handles the Notification according to preferences that were set. And not just social media, things like Apple News, retail/restaurant apps letting you know about deals that are on-going. Sports app pushing headlines. And so on.

For example, I've got most apps turned off for Notifications, so don't get a lot, but even with the few I do get, I'm sitting at about 14MB of push for half a month. Guessing Apple News (notifications off), ESPN (limited push via their app [eg. only for certain teams], maybe 5 a day, tops), a couple of restaurant apps (maybe a couple a week per app), Amazon delivery alerts (a couple a month to 2 months [not ordering a lot and usually one big order]).

Unfortunately, I do not think there is a way to easily find out what apps are getting push notifications.
 
I only have the enabled for signal and whatsapp, everything else is disabled. So you think I am still getting the data associated with apps I have disabled it for, but they just aren't being displayed or anything? I would have also assumed that the connections to the servers associated with push notifications would have also consumed data.

I am fine with not knowing what apps are responsible. As long as a data increase when I don't seem to have any notifications is expected.
 
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