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Raid998's profile



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Thursday, February 2nd, 2017 7:34 PM

SGH-I257 Samsung S4 mini

I bought an AT&T sim locked S4 Mini smartphone,

I requested an unlock code and my request got accepted, but the device is showing that the code is  wrong ("Unlocking is unsuccessful").

I've done some searches on Google, and I found some solutions that say I should enter the Unfreeze code (MCK) first, and then the received unlock code (NCK).

How do I get the MCK code ? AT&T only sent my the NCK code but the unlock process failed


Note : my phone is NOT rooted, and has the official firmware.


I hope I get some useful answers. Thanks


Community Support


207.3K Messages

6 years ago

Hi there @Raid998!


Thank you for joining our Community Forum page! I will be glad to assist you in answering this device inquiry. I can understand the importance of getting this device unlocked from our network in order to be used.


The MCK is referred to as a Master Code Key by Samsung Support. I apologize, AT&T only has access to the unlock code for your device. I would recommend rechecking the unlock instructions, which you may also view here.


If you are getting any error pertaining to the MCK code, please click here to gain further assistance. You may also need to perform a reboot on the phone. This would mean to power the phone off and back on to provide a refresh.


I would also like to confirm the unlock information you have received. I invite you to please send me a private message to @ATTMobilityCare. Please include your full name, unlock code, IMEI number, phone number, and a good time to contact you back. This way, I can gather additional information and research the matter further.


I hope this information helps to answer your question, and I look forward to hearing from you. Please have a good weekend and take care!


Shenoah, AT&T Community Specialist

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