Once you "unlocked" a T-Mobile (pre-paid) phone, does it STAY "unlocked", even if you do a factory reset?

[VirtualLarry]

I had this phone, and used it on T-Mobile FlexPay and Pre-Paid for a while. It was a good little phone. Anyways, I think that I unlocked it, while I had it. At least, it was either this phone, or the next phone, that I unlocked, kind of forget which. It had the unlock tool on the factory ROM, you just needed to run it after using the phone for so many months on pre-paid. Now that I think about it, I may have migrated the SIM to my other phone, BEFORE I ran the unlock too, so this phone might still be locked. I want to use it with a AT&T MVNO / reseller plan.

Is there some sort of code to punch in to see if it's unlocked?

 

[isekii]

yes once you unlock it should be permanent