Phone model and authenticity is unknown

[redongashi16]

Hello,i have been trying to flash stock firmware on my Galaxy S6 but i haven't been able to do it.While i was digging a solution i noticed that i can't tell which variant of the S6 my phone is.I have been trying to flash SM-G920F firmware until now.I bought the phone 5 days ago at a local mobile shop&service.The real problem now is that i can't tell what has happened to this phone before i bought it.
Back cover of the phone says that my phone is SM-G920F.
It is shown as SM-G920F in phone settings too.
When i enter download mode,it says my phone is SM-G920P.
I have downloaded the "Phone info" app and it says my phone is SM-G920P.
The IMEI is the same everywhere(in the back of the phone,in settings,in "Phone info" app,when i dial *#06# etc.)
I tried looking the IMEI up online and Check IMEI - IMEI.info says my phone is SM-G920F,however the S/N number is not the same as in the back of the phone and in "Phone info" app.The phone settings also show a serial number that differs from the back of the phone and that number is the same as the "Phone info" app number.
Can someone help me?
I have attached screenshots of everything.

 

[B. Diddy]

Let me see if ironass (our resident Samsung guru) can help you with this.

 

[ironass]

Only one quick question to ask... What network are you using it on?

 

[redongashi16]

I am using it on Slovenia network Mobitel

 

[ironass]

I am using it on Slovenia network Mobitel

If it is fully functional on your network's 4G band, then it will be the G920F model. If not and your network supports 4G, it will be the CDMA model, G920P, for the U.S.A's Sprint, CDMA network, which does not work on European 4G.

Looking at your screenshots, my guess is that you have the CDMA Sprint carrier minority variant with a custom global firmware flashed to it somehow. If so, my recommendation is to leave it as it is unless you are a expert or competent firmware flasher and rooter.

 

[redongashi16]

My network supports 4G and it works,however when i enable 3G or 2G it still shows 4G on notification bar.I tried to flash stock G920F firmware but i was not able to do it,i have a 30 day warranty which means that i can return the phone and that's probably what i'm gonna do.I think i can flash G920P firmware but that will probably corrupt my modem/EFS which will lead to network not working in Europe and that will probably void my warranty so i haven't tried it yet.

 

[ironass]

I certainly wouldn't recommend flashing CDMA firmware when you are on a GSM network. Returning it is, in my view, the safest bet.