Lumia 1020 unlock question

[Orcus]

I have an odd situation. I ordered two 1020s for my wife and I and got unlock codes from AT&T once they arrived. The weird part is that once I put in the new Net10 sims I have never been prompted to unlock the device. They both work fine for voice, text and data without unlocking; MMS is not working but I haven't invested much time yet trying to work that out. This doesn't sound normal from my reading on this forum and XDA. Is there something I need to do to unlock them? Should I be concerned about my phones suddenly stop working, or the unlock codes from AT&T expiring?

Thanks in advance for the advice!

So far my wife and I are loving our Lumia 1020s and the Windows Phone 8 platform. We're very glad we went this route.

 

[Orcus]

Just in case anyone else has this question, Palandri replied to my situation in another related thread and explained that because I'm using a MVNO (Net10) that uses AT&T the phone doesn't have to be unlocked. I'm going to pop my still working T-Mobile sim in the phones to unlock them in case I choose a different carrier in the future.

Thanks Palandri!