Got the official "we've unlocked your iPhone" email, please wait 24hrs from AT&T. It's now been 72 hours and I have backed up and restored multiple times but my T-Mobile sim still won't work (works in another unlocked iPhone so it isn't the sim). I've done the unlock with the AT&T sim inserted as well as the T-Mobile sim but always get the "invalid sim" message. Tried it on both a PC & a Macbook. DO I need to request a second unlock from AT&T or is there another way to do the backup and restore that might trigger the unlock?