My S3 doesn't like my operator anymore

[hamradio64]

Hi,
my no-brand Galaxy S3 GT-I9300 was working fine running CyanogenMod-13.0 nightly with my Vodafone Italy sim card, until I used for some weeks a sim from the italian operator Tre. When that contract expired I discovered that my phone didn't accept anymore sim cards from the italian operators Vodafone and Wind (it shows a message complaining that there is no sim card), while it works fine with the italian operators TIM and Tre. Sim cards that my phone doesn't accept are well working in other phones.
Previously all sim cards of all operators where working fine.
I tried the following with no result:
1)- wipe all user data;
2)- install the original Samsung firmware JSS15J.I9300XXUGOE1, followed by another wipe user data;
3)- restore from a full nandroid backup, including modem, system, user, cache partitions and EFS, taken when everything was working fine.
I've checked my IMEI number on some websites and it seems to be clean.
All the hardware in my phone, including the sim card reader, should be fine because everything works when inserting TIM and Tre sim cards.
Can anyone give me some help?
Thank you in advance.

 

[Rukbat]

About the only thing that comes to mind is that one of the cards somehow SIM-locked the phone, which should be impossible. (The firmware and data have nothing to do with the SIM lock.)