1. Windows Central Question's Avatar
    I have a valid AT&T unlock code for my device. I have entered the code via using another SIM card and the ##7820#.When the SIM card is inserted (Walmart Family Mobile T-Mobile towers) the message "SIM ERROR" is displayed. I tried a 2nd WFM SIM card, same issue. I discovered the ##7820# with no SIM card inserted and when I enter my 20-digit code, the locked symbol shakes back and forth. I cannot get the code to work. AT&T customer service guarantees the code with my IMEI number and won't issue another code as the code provided is unique to my IMEI number.
    01-15-2015 07:22 PM
  2. L Beezy's Avatar
    Bear in mind that you only have 3 attempts to correctly enter the unlock code before your phone is permanently locked to the AT&T network. Hopefully, you haven't attempted 3 times...
  3. fitchalcyone's Avatar
    From my experience, I've unlocked four Lumia phones with AT&T. Each time I've just done it without a foreign sim card inserted and via the ##7820# without any issues whatsoever. I hope you are able to get this resolved somehow. Have they verified with you that they have the correct IMEI number on their end?
    01-15-2015 07:30 PM
  4. L Beezy's Avatar
    Bear in mind that you only have 3 attempts to correctly enter the unlock code before your phone is permanently locked to the AT&T network. Hopefully, you haven't attempted 3 times...
    01-15-2015 07:36 PM
  5. PaulFSemicolen01's Avatar
    they have confirmed verbally they have the correct IMEI number and the unlock code they gave me is tied to that number.
    01-16-2015 03:58 PM
  6. PaulFSemicolen01's Avatar
    when the new sim card is inserted it says I have 10 attempts. When I tried the ##7820# way, there is no "attempt counter" and I have entered the code correctly, check and rechecked before pressing the check mark to attempt the phone unlock. the previous owner is my coworker, and he bought the phone new and has always been an AT&T customer. (Just a little further info in case there were questions). Does the lock shaking when the code is entered imply an invalid code or permanent lock of the device?
    01-16-2015 04:02 PM
  7. PaulFSemicolen01's Avatar
    okay, now something weird happened. I turned my device on and dialed ##7820# to show my coworker my issue, and the phone showed it was unlocked! Great! So i put the sim card in and reset the phone. However, the prompt for unlocking the phone popped up again. when I reenter the code it still says "SIM ERROR".... WTF!?!?!?!
    01-16-2015 06:23 PM
  8. tai4de2's Avatar
    Sounds like maybe the SIM card itself went bad, I've had that happen. Does it work in another phone?
    01-16-2015 06:42 PM
  9. PaulFSemicolen01's Avatar
    One thing we are thinking might be causing the issues. I upgraded the the phone to Windows 8.1 developer preview. I will download the Nokia Lumia recovery tool and factory reset back to Windows 8.0 and start the whole process over again...
    01-16-2015 06:53 PM
  10. PaulFSemicolen01's Avatar
    Sounds like maybe the SIM card itself went bad, I've had that happen. Does it work in another phone?
    I continue to use the SIM card on my Walmart Family Mobile phone as it stands until I can get the Nokia 920 Unlocked. I tried another WFM SIM yesterday with the same results
    01-16-2015 06:55 PM
  11. MDK22's Avatar
    Bear in mind that you only have 3 attempts to correctly enter the unlock code before your phone is permanently locked to the AT&T network. Hopefully, you haven't attempted 3 times...
    The OP is correct - you have 10 attempts before the phone is permanently LOCKED. Use them wisely ...
    I assume you wiped the phone, originally, to enter your account - IF not, did the previous owner have a sim password set?
    01-16-2015 07:01 PM
  12. PaulFSemicolen01's Avatar
    The OP is correct - you have 10 attempts before the phone is permanently LOCKED. Use them wisely ...
    I assume you wiped the phone, originally, to enter your account - IF not, did the previous owner have a sim password set?
    Correct the phone was completely wiped before i got it. Following me acquiring it before I received an unlock code, I decided to set it up in wifi mode the way I wanted it to prepare for the long wait from AT&T. my coworker and I think the developer preview 8.1 may be messing with the process. I am going to try to factory reset it back to 8.0 when I get home from work tonight.
    01-16-2015 07:42 PM
  13. fitchalcyone's Avatar
    I unlocked my yellow 1520 during a point when I installed Developers Preview on it. Then, when I sold it to a friend, I used the Software Recovery Tool to bring it back to 8.0 as he wouldn't be familiar with the side updates. This locked the phone again, but the old code still worked and unlocked the phone just fine.
    MDK22 likes this.
    01-17-2015 03:06 AM
  14. MDK22's Avatar
    I unlocked my yellow 1520 during a point when I installed Developers Preview on it. Then, when I sold it to a friend, I used the Software Recovery Tool to bring it back to 8.0 as he wouldn't be familiar with the side updates. This locked the phone again, but the old code still worked and unlocked the phone just fine.
    ^^^ VERY IMPORTANT ^^^ so make sure you save the code, somewhere. Check after phone updates, also.
    01-17-2015 08:07 AM
  15. MDK22's Avatar
    Correct the phone was completely wiped before i got it. Following me acquiring it before I received an unlock code, I decided to set it up in wifi mode the way I wanted it to prepare for the long wait from AT&T. my coworker and I think the developer preview 8.1 may be messing with the process. I am going to try to factory reset it back to 8.0 when I get home from work tonight. then unlock, then upgrade to Dev Preview, then check for unlock (if needed)
    RED comments
    01-17-2015 08:09 AM
  16. MDK22's Avatar
    Bear in mind that you only have 3 attempts to correctly enter the unlock code before your phone is permanently locked to the AT&T network. Hopefully, you haven't attempted 3 times...
    Sorry, Beezy, you're thinking about Phone sim Password ...

    MODS - who picked this as Best Answer, it's not even correct.
    01-17-2015 07:36 PM

Similar Threads

  1. More reports of Lumia Denim rolling out to additional Lumia 930 devices
    By WindowsCentral.com in forum Windows Central News Discussion
    Replies: 1
    Last Post: 01-15-2015, 08:10 PM
  2. Microsoft drops Xbox One price back to $349, hints at gaming focus in Windows 10
    By WindowsCentral.com in forum Windows Central News Discussion
    Replies: 0
    Last Post: 01-15-2015, 06:42 PM
  3. Know where your Country Variant Lumia comes from for OS updates #LumiaDenim
    By WindowsCentral.com in forum Windows Central News Discussion
    Replies: 0
    Last Post: 01-15-2015, 06:42 PM
  4. myTube 2.0 completely rebuilt with 1080p, 480p and 60 FPS for YouTube!
    By WindowsCentral.com in forum Windows Central News Discussion
    Replies: 0
    Last Post: 01-15-2015, 06:42 PM
  5. How do I find the WPS pin code on my 920?
    By Windows Central Question in forum Ask a Question
    Replies: 1
    Last Post: 01-15-2015, 05:54 PM
LINK TO POST COPIED TO CLIPBOARD