The reason I'm asking is that my company design mobiles phones (and many other things) so I have all the equipment to write on SIM cards, read them, etc...

Obviously the TurboSIM copies some bytes from the AT&T card and combine them with the SIM from your mobile provider

Question is: What is required ? Which bytes to copy, which information. Where kind I find a tutorial on this?

So I could my own SIM, merging info from my Telstra SIM card and the AT&T one..