First thanks for your time and Hope you can help me.
I receive my Samsung S8 Plus, I bought it on samsung.com with AT&T as carrier and I paid the full amount ($850) to avoid contracts and unlock the phone and use it with my phone network provider. (I live in Mexico)
At the beginning it was asking just for the “network unlock code” I tried to use the official site to unlock the phone (https://www.att.com/deviceunlock/?#/) but for some reason when I put my IMEI it was showing that my IMEI was not in their system.
After some failed attempts my phone start asking me the PUK code as well, “SIM Network Pin Blocked. Enter SIM network PUK”
So I paid to the guys from www.unlockbase.com to get the unlock code and unfreeze but It didn´t work.
They send me 2 different codes, Network code and Unfreeze code. They told me that the Unfreeze code was the same as PUK code but It wasn’t and my phone is still blocked.
3 days ago for strange reason I tried again in (https://www.att.com/deviceunlock/?#/) and finally my IMEI was in their database. They already sent me my unlock code and is exactly the same as from www.unlockbase.com but as my phone is asking me for “SIM Network Pin blocked. Enter SIM network PUK” I can´t unlock the phone.
I also tied with a different sim cards and the phone displays the same message asking for the PUK code.
I´m desperate I really don´t know what to do.
My guessing #1 is that maybe if I use Odin to install a new firmware from the phone I´ll get rid of the message “SIM Network Pin blocked. Enter SIM network PUK” and I can finally use the “network locked PIN” to unlock my phone. Or maybe use a Firmware that is not from AT&T.
My first big question is; Can I use any Samsung Galaxy S8 plus firmware as long as is the same model? (In my case is SM-G955U)
I´m not sure If the PDA or CSC is mandatory or not.
My second guessing is to buy a USA AT&T sim card and check if the phone is still asking me for the PUK code. If I have a USA Number, AT&T USA can give me a PUK code and maybe it works to get rid of the message “SIM Network Pin blocked. Enter SIM network PUK” and use the other code that I already have to unlock the phone.
I´m in Mexico so I can´t bring the phone to an AT&T store, I have to fix it by myself.
So I don´t know if you can give an advice or a solution, I really don´t know what to do anymore.
I would really appreciate your help!!