If you want an iPhone 4S but don't want to give up your T-Mobile contract and switch to Verizon, AT&T or Sprint, you're not entirely out of luck. All you have to do is follow two hackers' directions.
On Pastebin and in a YouTube video, hackers Michael Capozzi and Daniel Scaleb posted step-by-step instructions showing how to hack an iPhone 4S and make it compatible with T-Mobile, the major U.S. carrier that doesn't support the Apple smartphone.
The modification requires a user to insert the original AT&T SIM card, dial 611 for customer service and then drop the call. The next step involves turning on "Airplane" mode, removing the legitimate SIM card and inserting a T-Mobile SIM card.
Scaleb writes on Pastebin that the next step is to switch off "Airplane" mode, which will cause the iPhone to search for a network. The EDGE network will activate automatically, after which the user should turn off the phone after 20 to 30 seconds, turn it on again, and tap "Use Cellular Connection" when the "Activation Required" screen pops up.
From there, ejecting the SIM card and reinserting it should unlock the phone and make it compatible with T-Mobile's network.
The modification seems simple enough, but tech site Gizmodo, which was among the first sites to report it, said it has received conflicting reports about whether or not the unlocking trick works.
If you want to avoid the hack and get a T-Mobile-compatible iPhone 4S, there's another way: as of last week, unlocked GSM iPhone 4S smartphones are available for $650.