Question,... I bought an iPhone 6 from a relative, knowing it had a year left on contract, expecting to keep it in his name and make $105.00 a month payments. Unfortunately, his account is actually suspended, $500.00 to get it re-activated.
If I unlock this phone with a paid service, will AT&T be able to prevent me from using T-mobile? Or do I now own an expensive iPod.
P.s. I checked on apple site to verify it was not "blacklisted" if that matters.
Cant say if AT&T will prevent you or not, I have seen a iPhone that was blacklisted on other networks except AT&T's own, I think they do that to keep you using their service instead regardless you use it on the same plan / account or not.
and Blacklist status with other carrier's is unrelated to unlocking, so even a Unlocked phone can be blacklisted with some carriers and work on others.
Lastly, there is no way for ANYONE to check on Apple site if the phone is blacklisted or not....so I'm not sure where you got that assumption from.