If you still own one Encrypted iPhone in any network of a foreign operator, or if you want to purchase a new iPhone, then you will probably be interested in finding out what is the current situation of the possibility to do decoding for iPhone. Unfortunately, for more than 3 years no solution has been released decoding for iPhone, and considering the way things are evolving now, the launch of a new solution by unlock for iPhone seems unlikely.
At the moment, the decoding is done, mainly, either using old solutions such as ultrasn0w, for those with compatible basebands, or decoding tickets for SAMor decoding cards or permanent decoding. Permanent decoding for iPhone is sometimes the only solution for using an iPhone, but unfortunately if you have one iPhone locked with iCloud/Activation Lockthen activation to be impossible at the moment.
Having said that, here is the current situation, and for everything you have described below you have tutorials on this page.
iPhone 3G and iPhone 3GS
Decoding for iPhone 3G or iPhone 3GS is possible using ultrasn0w if you have the old basebands, or iPad baseband, this tutorial helping you to unlock without problems in any conditions, including using SAM tickets this tutorial. In the case of these terminals, there are no problems for decoding, even if they no longer run the latest versions of iOS.
iPhone 4
If you baseband 01.59.00 you can do decoding for iPhone 4 using ultrasn0w, but if you don't have this baseband, you only have the option of using one decoding card, if you have lower baseband 04.12.x. In the rest of the cases, decoding with SAM tickets, if you already have them, or permanent decoding remains the only solution for using the terminal. Unfortunately the recent decoding cards cannot do it unlock for iPhone 4, so it is good to avoid them.
iPhone 4S
Regarding iPhone 4S Decoding the situation is similar to the one described for iPhone 4, except for the possibility of using ultrasn0w. iPhone 4S can be cracked using SAM tickets, if you have them, or various ones decoding cards which are generally compatible with iOS 6 or iOS 7, permanent decoding being the safest solution to obtain a fast decoding for your terminal regardless of the situation.
iPhone 5, iPhone 5C and iPhone 5S
For these devices there has never been a software solution for decoding, the only methods to do it unlock being decoding cards or permanent decoding. In both cases you can decode almost anything iPhone 5, iPhone 5C or iPhone 5S from the planet, with the exception of a few networks from some Asian countries that cannot be decoded.
Basically, the biggest problems are with old iPhones, because new iPhones are much easier to decode.
