how to block an OS app popup? Something on my smartphone sends a message once a day, sometimes I see a tiny fast dark background popup on the bottom saying it is doing so.  

Such application seems related to the SIM card, as the popup I receive is from my cell phone provider/carrier/operator.

One second later I receive this:  



The app name is "Serviços TIM".
That app package name is "com.android.stk" (I found that using Brevent).
It is an OS App.
It has the exactly same version of "SIM ToolKit" (I guess .stk means that), but at apps list it is in an independent entry with it's own options.

The real huge problem is that, when that popup shows and the screen is locked and remains like that for 8h+, the screen WILL NOT TURN OFF and will spend my battery from 100% to 40% or less and I may depend on having the battery at that time! :(. I usually let it out of the charger, and without that popup it would only spend about 5-10% of the battery.

My smartphone J7 is not rooted, I wonder if that would be the only option?



update:   



This other app I think is the culprit from sending the message. It already had SMS disabled but not the phone permission! (I have other app to let me read/send SMS btw)


also the SIM toolkit, I force stop it (and disabled all notifications now 2019):




Final result is: none of these actions above worked, the popup still happens :(
I managed to minimize the problem by using the "do not disturb" feature.
By "minimize" I mean that if I am using the phone the popup will still show up, otherwise it wont mess it's battery (neither show up).
I can allow all exceptions least "reminders" apparently.
Obs.: "do not disturb" is not 100%, I think about 10% of the times it will still allow that abusive popup to keep the screen ON for many hours!

The simToolkit app package "com.android.stk" (which I found out using Brevent), is called "Serviços TIM" and seems to be a mirroed/dup (???) package from the default simToolkit.  

My next step (as soon that popup annoys me enough) is to try to uninstall that package by using this tip by @Izzy, thx!
How to remove the SIM Toolkit from my phone? (Without root or flashing any ROM)

adb uninstall failed
Uninstall via adb without root
How to disable Google Apps in Mi Phones
Did it finally:

adb shell pm list packages |grep stk

adb shell pm path com.android.stk
adb pull /system/app/Stk/Stk.apk # to backup it just in case

adb shell pm path com.android.stk2
adb pull /system/app/Stk2/Stk2.apk # ...

adb shell pm uninstall -k --user 0 com.android.stk
adb shell pm uninstall -k --user 0 com.android.stk2