After some months of just to avoid solving the problem, I am keen to get it done. My problem is : I can´t use other carriers in mi Xiaomi 4, just 1 carrier is allowed. This is a surprise, as before I could use a different carrier at least ( I didn't try all the different carrier's sim cards on mi xiaomi 4, there are like 4 carriers in my country, but I did it with 2). I think I caused the problem accidentally: One day I was just changing the sim card for a new one of another carrier ( both carriers were working before, I tried them, but I just used one in my daily use), but I pressed something ( the power button and volumen)...then, I realize the screen with a different format ( Reset and boot screen )...at that time I didn't know anything about that, so I just remember I turn it off...or something like that...and when the cellphone restarted, I couldn't use anymore the carrier I was using before, it appeared as '' no service '' . Then, I tried with all the other ones ( buying new sim cards )....and just one got it. When I saw the mobile networks ( in settings), just my current carrier was allowed, and others have a '' (FORBIDDEN ) '' next to them. The weird thing is that my phone worked before with a carrier, and after that accident, It couldn't use other carriers anymore including that old carrier...it made me to buy a new sim card and change carrier. I already made the recovery through settings, later in Recovery '' power+ volumen '' I did already the 4 wipes...and finally, I Rebooted with System 1 ( latest) and System 2...but noyhing solved. It is not a problem of the bands. Before I buy the Xiaomi 4, I made sure It will work here with my country's bands...and actually, it did, but after this accident, it is '' (FORBIDDEN ) '' Please, could you help me ? I am desperate! PD: I never changed any ROM or something like that. Thanks a lot !