My two-year contract with AT&T recently came to and end and I decided to take them up on their recently announced ability to unlock an out-of-contract iPhone. If for no other reason than to make my phone easier to sell to someone who may want to use it on another carrier. Note that this is NOT a jailbreak and has nothing to do with jailbreaking. This process was performed on an un-jailbroken phone that was out of contract (meaning I've paid in full for the phone and now completely own it).
There's a lot of confusion about this process and how it works. There's also no way to verify that your phone is in fact unlocked. Thanks to T-Mobile, you now can for 99 cents. Here's how:
Step 1: Request the unlock from AT&T
I did this via webchat and the AT&T rep was quick to understand what i wanted and performed the unlock right away.
Step 2: Backup and restore your phone via iTunes
Some online forums lead me to believe that the communication from AT&T to Apple to my iTunes to my iPhone may take a few days, so i waited three days to perform my backup and restore. I also read on the Apple support forums that you'll receive a message upon successful carrier unlock but I did not.
Step 4: Trim your SIM to make it a MicroSIM
I've read that if you have a T-Mobile store nearby (I do not) that the salespeople there may have a tool to do this for you. There's a few guides online that describe this process
, if you're a DIYer like me. If you screw it up, you're out only a buck. I used my Swiss Army knife's to score the SIM then the pliers to snap off the extra pieces. Then used a file to grind and smooth the edges.