I've been working on ASIdentifierManager framework to get the new UUIDString, the identifier should replace in iOS 6 the UDID, and can be stopped or not by the user for Settings. Everything is ok on simulators and iPhone 4S, but on iPhone 3GS (it's iOS 6 updated!) I'm getting as UUIDString the following: 00000000-0000-0000-0000-000000000000 This is how I'm getting it: if ([ASIdentifierManager sharedManager]) NSLog(@"%@", [[[ASIdentifierManager sharedManager] advertisingIdentifier] UUIDString]); Does anyone know why? Have you encountered this problem? Thanks