My S20 is asking for MCK code, I contacted AT&T but they sent me the NCK only. I can't unlock my device. I spent hours on contacting AT&T and Samsung but still no solution I can't use T-Mobile SIM.
AT&T support said: Unfortunately, we don't have access to an MCK code for your cell phone, so we're unable to provide you with that information.
I have contacted Samsung support multiple times and they said that the MCK code is something that AT&T have to provide to the customer.
Will someone please help me?