I bought an iPhone 4 from a friend and he told me that its officially unlocked! the iphone work with any sim card. The problem is that I found that Ultrasnow is installed & my baseband is 04.12.02 I know that Ultrasnow unlock iphone 4 with basebande 1.59.00. But when i deleted Ultrasnow the iphone become sim locked and don't work with any sim card. Then I reinstalled ultrasnow, the iphone work's again with sim cards. I want to know what is the problem & if my iphone is officially unlocked I tried with IMEI.com website but give me nothing! Now my iphone is on ios 5.1.1 baseband 04.12.02.