elaborate please! My understanding is that simcards are made or manufactured based on agreed internation standards. As long as a company anywhere in the can make a simcard based on standards, it is good to go. This simplifies the process mobile phone manufacturer or modems company take to make there products work with a branded bt standard based simcards.
Where as 2g simcards where is to make, there was a lot of problems with them, the major one being cloning. 2g lacked authecation to base stations and people encured massive bills from criminals. 3g resolved all those problems, added more layers of security and a lot more functionality. Thus why its very important to adhere to strict manufacturing standards.