I am using Fairphone Open 18.04.1. In the last two months (that’s how long I own a FP2) I got billed 50€ by my provider (o2 Germany) for data usage. The problem is, mobile data is switched off and in the Settings-> Data usage shows that no data is used (except for the 2 or 3 times I actually used it.)
A couple of questions:
About phone-> Status-> SIM status-> Service state says that “Voice: In service / Data: In service”. Is this expected if data usage is switched off?
Is it possible to obtain more detailed logging about data than provided by Settings->Data usage? Maybe from the command line?
I found this interesting answer on stackexchange. Partial quote: "You may have mobile data disabled and restricted and yet this switching back and forth from 4G to 3G uses small amounts of data each time."
This could be the problem. Has anybody ever heard of such a thing?
Any other ideas what to check? (Of course I will contact my provider, but the support guy told me that the only way to inquire about an invoice is to send a letter by snail mail somewhere. So it will take time until I hear from them.)
No, it’s not related to roaming. My data plan is per minute, capped at 3,50 € per day. On some random days the invoice claims that data was used 40+ minutes, which yields the daily maximum price. Some of these incidences are at times where I am sure that I didn’t even touch my phone (e.g. at night).
Well, for me, status shows the same as you. It seems, that data switch is in “Status of mobile network” (Status Mobilfunknetzes) two rows below: When this is “Not connected”, then data usage switch is set to off (and I hope it is off), if it is “connected” then data usage is set to on. No difference of 3G/4G setting or connection.
Wow, thanks for sharing. Good reason not to use O2. Anyway, I suggest you not only ask for an invoice but also for the detailed records when and how long your phone was using mobile data (“Einzelverbindungsnachweis” in beautiful German).
And another guess: Did you send or receive any MMS?
Finally, I hope you disabled data for both SIM slots/cards?
It get’s funny. On the hand, today I got a quick reply by e-mail. On the other hand, it was completely unhelpful: They just said, that their systems are ok and that modern smartphones are complicated. I tried to reply to their e-mail to ask for some technical details, but it seems to be impossible, I got the auto-reply: “Diese E-Mail-Adresse steht leider nicht mehr zur Verfügung.” Now I have to send a letter again. (Just to mention, I think you get O2-support on Twitter and Facebook, but I refuse to use these platforms.)
Anyway, I now believe more in my suspicion, I found another interessting link, which refers to the point about 4G/3G a mentioned in the first post.
So, I will try to switch off 4G and see if it helps. Am I really alone with this problem? My particular issue seems to be, that my data plan is by time not by volume. If you’re billed by volume, you might not notice that I few bytes get eaten away. But by time it amounts to something substantial. Is it possible, that no one has time-based data plan nowadays?
They are very unusual, I have not seen any adverts of such tariffs in the last years. And they don’t really fit with the normal smartphone usage (“always online”).
All right, the issue is now resolved. After my second inquiry I actually got a nice reply from O2/Telefónica. They confirmed that it is indeed a problem related to 4G. The take home message is, that if you have an old data plan which bills you per minute, then you should switch Settings -> More -> Mobile Networks ->Preferred network type to “3G” and not to “4G”.
The problem is, mobile data is switched off and in the 
(Just to mention, I think you get O2-support on Twitter and Facebook, but I refuse to use these platforms.)