I own a 3gs..I upgrade with a custome 4.2.1 and unlock with ultras0w..everythin works fine few days...no I conect to itunes to sync to get my photo library...after that I lost my carrier signal..."No service" I try to unlock it again with ultrasnow and a message said Coulnd activate cellular data network . and other messaje was "you data network is not longger available In the setting the carrier option is intermitent working and I only can see claro and ATT but not my carrier that is Tmobile