A quick question. Would this work on a Sprint phone that's unlocked to T-mobile? Thanks!
First question is unlocked how?
I ask this because to my knowledge Sprint is not unlocking their iPhones even after contract and even buying full price they are not unlocked.
And if it was unlocked via using a jailbreak then according to t-mobile this update won't work
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Yes it is dishonest. Even if it works, it probably will not (you didn't get it from T-Mobile), why should T-Mobile pay for you to have a new phone? Suck it up, and sell the phone when the 5s comes out.
And it may backfire. The carriers often use refurbs for their insurance replacements which means you'd get a phone produced preswitch.
And Apple may have two service parts for these phones based on the serial and under terms the customer agreed to they wouldn't have to flip you to the newer one because the coverage is for identical hardware to what was purchased.