unlocked att lumia stopped working after windows 10 upgrade

[Windows Central Question]

I have a att locked lumia 520 and i got it unlocked and was using tmobile sim on it. I upgraded software to windows 10 and since then i am unable to use tmobile with my lumia.

I even tried entering the code manually by dialing ##7820# and then entering the code. It does show unlock symbol, but does not actually show any network.

 

[xandros9]

The Lumia 520 was never supposed to see the official upgrade to Windows 10 Mobile. If it was installed by way of the various spoofs/hacks available then you've entered dangerous territory. Does it work with any other SIM perhaps?

 

[abhishek singh21]

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