I have an iPhone 4S that I am selling (just bought the iP5) and had unlocked ... I went through the entire process after I received my confirmation of plugging into iTunes and doing the restore and once completed I got the screen stating "Congratulations, Your iPhone has been unlocked" I am confident of course that this phone is now unlocked but other then say putting in a valid T-Mobile sim to make sure it works on that network is there any other way to know for sure that this is unlock is indeed complete? My buyer lives out of state and I would really like to be able to confirm the unlock works 100% prior to shipping (he is only using on T-Mobile so if it doesn't for some reason we will have to go though a not fun process of returning etc. etc.) Thanks so much for the info guys.