In my limited understanding, the phone is either locked or unlocked, there is only one "carrier subsidy lock" regardless of what it is being called. If anyone tried to unlock the code, and failed to do so in five attempts (wrong code or just hitting the wrong numbers) after those five attempts the phone "blows a fuse" and something internal changes, permanently locking the phone to the carrier.
Both AT&T and Motorola swear this is how it works. Five tries to unlock, and then something is permanently changed and nothing, no reset, no reprograming, norhing can ever unlock the phone again. You would think it is just code, code can always be changed, but they say no, this code is one-way, one-time, one shot and it is as permanent as a fuse blowing.
So if you bought a used phone, the previous owner may have blown this. If you bought an unlock code and it was incorrect, you may have blown it. The total of five tries is cumulative, for the entire life of the phone. If the PO got it wrong three times and you get it wrong twice more, a year later? It is still "blown" forever.
I can't swear this is true, only that AT&T and Motorola both swear it is. Not just the bottom level techs, but the executives as well. All of them.
A locked phone may not show an error, for instance, an AT&T phone using a T-Mobile SIM will show a "network error" if you try to use it. It will not say anything about the real problem, being locked to the original carrier.
Solution? Sell the phone, buy one that is unlocked. Sorry, but that's all there is to do if you've hit the "five" limit.