My note has some weird problem with the modems. I'm getting "Unknown" baseband, modem verison, phone number, IMEI etc. with all the modems I tried except one, which shows the correct IMEI and modem version but still not working(I can even see the mobile networks with that one, but I it doesn't connect and gives me "Refresing SIM data" messages).
One day, some months after the last rom update, started to lose the phone network conection and I was getting pop-ups with "Refreshing SIM data"(was very annoying because that was turning on the phone screen every few minutes). Sometimes I had phone network and sometimes I hadn't. The disconnections became more frequently. The phone also started to eat up the free space for apps, so I had to remove several apps to install or update even a small one.
So I decided to change to a different ROM to see if that fixes both problems, but I got the actual problem.
I was in AllianceRom v3 JB when that happened.
I flashed this AryaMod 5.5 JB following their instructions and I got this weird problem. In the "About phone" says that the Baseband version, IMEI, IMEI SV, Network and My phone number are "Unknown". I can't even search for mobile networks because it says "Insert SIM card" when I try to open the Mobile networks menu. Tehre are no signal bars, only a "denied" icon on the status bar.
I tested all JB modems and some from ICS from the "all modems" thread, but I was getting the same "Unknown" things in each one, except the XXLSO, where the Baseband version, IMEI and IMEI SV were okey. I could also find mobile networks with this modem, and the "Refreshing SIM data" thing returned, but it was not possible to connect to a network. With this one, there aresignal bars, but they are empty.
I flashed the AllianceRom and even the old ICS rom I had before, but the problem persisted, even with the modems they came with.
Now I'm on the latest Samsung rom(LT4), unmodified and flashed with odin and the problem persist.
I found this old thread. His initial problem is very similar to mine, but they don't know what caused it nor how to fix it.
I have also found something about corruped IMEIs that you can fix doing something with the ADB and restoring EFS folder, but I think that is not my case because I can see my original IMEI with the XXLSO modem (and I my EFS folder looks OK, anyway I have no backup of that).
I don't expect to get a step-by-step tutorial about how to fix this, but I hope somebody can put me in the right direction. I will post the solution if I find one!