CPU, flash ic change....looking for info
 

I know it will be maybe stupid to ask but i wanted to know, if anyone change the cpu or flash ic in iphone. i have one for playing and im thinking where is writen the information that phone is unlocked from factory. I wanted to know some things like if it have some information flash ic that u cannot put new, fresh or used one from another phone.i mean of course about the iphone 3g and 3gs