Trying to unlock at&t Nokia Lumia 1520 to use on T-mobile

[Idris84]

I have a Nokia Lumia 1520 that is locked to at&t. I used unlockusa to try to unlock it, and the came back offering me a refund because my code "could not be calculated or NOT available under normal process"
Firstly: What the heck does that even mean?

Secondly: Do you have a suggestion for me on how I can still unlock the phone?

Ps: I asked the person who sold it to me to get it through at&t and he said they didn't provide it, so that option is out.

 

[amb9800]

If you have a friend with an AT&T account, they can submit the unlock form on AT&T's site to get you an unlock code (5 issued per year per account, so not an issue for most people to spare one).