A friend of mine is planning to buy a 16GB 3GS via Craiglist. He wants to make sure he gets a 3GS, not a 3G, but he won't be able to boot it up and look at the system information until he has it activated with his own SIM (read: unlocking). Naturally he wants to be able to know whether or not he got the right model just by looking at the phone from the outside. Is it possible? TIA!