Question [Q] Using a diferent country firmare on Samsung Tab 3 SM-T211

I just bought a second hand Samsung Tab 3 7 SM-T211
When I start it up I've seen is from the network H3G ( 3 Italia)
However I put my Vodafone Romania sim card in it and everything worked like a charm, no network lock. I wonder why?

I don't like this H3G ( 3 Italia) branding and start up screen, and I found on sammobile firmwares for all the countries including Romania (Cosmote only) and I found also the Italian original firmware.

My question is what's happening if I write the Romanian (Cosmote) firmware on this Italian Tre tab?
Is that possible? I mean.. is the same hardware right? However they have different PDS CSC and MODEM types (see the images).

Another question: is there any risk to make my tab not working with my mobile carrier Vodafone? Maybe was networked locked on H3G ( 3 Italia) and after unlocked by the first owner, and if I write the firmware, I lock it back.. I really don't know.. That's why I am here, to get some information. Is there any possibility to find if it was network unlocked? Is there anybody from Italy to tell me if those tabs are locked on H3G?

There is another reason I want to change my firmware.

After some time, I realized I have to many missed calls, and when I call people sometimes is dropping the call.
Some people told me when they try to call me the call drops and they get a Network Error message on the screen.
I don't know what's that..

It may be a hardware issues or software? Any ideas?
Attached Images
File Type: jpg h3g_italia.JPG - [Click for QR Code] (36.2 KB, 11 views)
File Type: jpg ro_cosmote.JPG - [Click for QR Code] (36.8 KB, 10 views)