Yes...we have virtually no data service through tmobile where we are. Every once in a while we will get one bar or only an edge connection, neither of which are sufficient for clear calls or any type of Internet connectivity and it's not reliable to stay connected at all. I have to leave wifi on or I'm not connected at all unfortunately.
I just now revisited this thread, and realized that I totally missed this post.
If I read you correctly, you are using WiFi to get telephone access to T-Mobile ?? and this is because you have very little cell site service in your home..... I can sympathize, me too.... Make sure you keep DATA turned OFF.
if that is so, then you need to turn off, uninstall apps that are trying to talk home to momma..
I just went back and verified you have a Note 4, so I will ask you to install this app:
* Package Disabler Pro for Samsung
Now, once that is installed, boot it up.
Scroll down thru the menu, all of the apps will be in Alphabetical order.
If it is something you don't absolutely need, "Disable it". No harm done, it can be turned back on just as easy.
Anything with the name: Amazon, turn it off.
Facebook: OFF
any Social app: OFF
if you use Facebook/Twitter/Instagram: do it thru your desktop PC/Laptop preferably... as you are already "at home anyway". On the cellphone, use a browser, not their apps. Their apps are power hungry beasts of burden... turn them all off.
Ghostery is a very nice browser that will protect your privacy, and it stops adverts that drain the battery:
* Browser: Ghostery Privacy Browser - Android Apps on Google Play
Turn OFF all Notifications. All of them. Either do that in the app itself if it offers that, or go to:
Settings/Applications/App Manager/Downloads
Check each one and turn off the Notifications box.
Settings/Applications/App Manager/ALL
Check each one you did not turn off in Downloads and turn off the Notifications box.
If you use Email quite a bit, install Aqua Mail, and pay attention to the settings.
If configured correctly, it is very frugal of data use, IE, battery power needed.
Make sure Sync is OFF, it will poll the server for you email each time you bring it up. Make sure the Notifications is OFF.
* Aqua Mail - Android Apps on Google Play
All of what I am telling you, is exactly how I have my two S5 phones and my Note 4 configured....
and all of them give me very good battery life.
Once you have done all of the above, watch how the phone works for a week or so....
then as you get more familiar with Android, you can turn ON anything that is turned off and watch just that one app to see how that effects the battery life.
Please let us know if any of what we suggested helps.